A duplicate name has been detected on the TCP network

afthab:  Thank you for the quick response.

Do I have an alternative here?  If I do not want to change the name of my new laptop, or just want to clean up historical out-of-date information, can I de-register the old defunct laptop?  Or could this be that somehow my new laptop is registered twice?  

There was a lot of messing around recently when ethernet stopped working - though wireless was OK (probable conflict between AVG 8.5 and ethernet card - Realtek) - and the person who did the messing around (not me) might have set up duplicate networks, or heaven knows what else - they are not available to ask.

Thanks again

 

Well..
Do you have a domain or DC ?
what type of network u have, means strength number of PCs, do u have routers ?

it is never possible two computers with same name in a workgroup or domain.

They don't have to be in the same domain or workgroup. This is a netbios error. It means you have two computers on the same LAN with the same computername.

Try NBTSAT -a computername

afthab

Thanks again for the prompt response.  The setup here is a small network in a residential 2-story house that is wired for ethernet.  There are 4 computers that are usually wired directly to a modem/router by ethernet  - so no server, and I assume that is DC - if DC means direct connection.  Not if have a "domain",  but if that is a dedicated internet site/address then do not have one,  Three of the computers also access the network by wireless when not near an ethernet plug, or when the laptops are on-the-road.  The modem/router is plugged into the telephone landline though a splitter/filter).

The Belarc Advisor report (if you are familiar with that) states that my new laptop, that I am using right now, is "LRG-Laptop (in WORKGROUP). I assume that "WORKGROUP"is the default name of the local area network and the person who set this up originally never bothered to change the default.

If you would like more information, please advise how I can access that information (ipconfig? Network and Sharing Center?)

Thanks again

ChiefIT:

Thank you for pitching in.  The nbtstat report, if that is what your posting referred to, is set out in my original  posting.  My recently deceased laptop MAY have had the same network name - not sure.  From first response I got, apparently I can resolve this by changing the name of this new laptop that I am presently using.  However, I am trying to find out how to clean up NetBIOS and rename or deregister names no longer in use - and maybe retain the name on this computer "LRG-laptop".

Thanks

OK, they usually go away in about 15 minutes. Netbios broadcasts will be sent to throughout the LAN about every 15 minutes per PC and 5 minutes per server.

Netbios cache can hold these records for a while.

You might try flushing your netbios cache. To do so, type NBTSTAT -R. If you have a WINS server, you will also want to type NBTSTAT -RR.

Also, LMHOST files can cause this issue. LMHOST files are WINS equivallent to DNS HOST files.

So, you might have an old LMHOST file record or this record residing in cache.
____________________________________________________________________
To see if this computer still exists. Go to the command prompt and type: " Net view "
That will list all active computers. If it still exists, type: Ping -a computername for the IP address.
____________________________________________________________________
Here are a list of NBTSTAT switches that could help you run through finding netbios discrepancies.

NBTSTAT [ [-a RemoteName] [-A IP address] [-c] [-n]
        [-r] [-R] [-RR] [-s] [-S] [interval] ]

  -a   (adapter status) Lists the remote machine's name table given its name
  -A   (Adapter status) Lists the remote machine's name table given its
                        IP address.
  -c   (cache)          Lists NBT's cache of remote [machine] names and their IP
 addresses
  -n   (names)          Lists local NetBIOS names.
  -r   (resolved)       Lists names resolved by broadcast and via WINS
  -R   (Reload)         Purges and reloads the remote cache name table
  -S   (Sessions)       Lists sessions table with the destination IP addresses
  -s   (sessions)       Lists sessions table converting destination IP
                        addresses to computer NETBIOS names.
  -RR  (ReleaseRefresh) Sends Name Release packets to WINS and then, starts Refr
esh

  RemoteName   Remote host machine name.
  IP address   Dotted decimal representation of the IP address.
  interval     Redisplays selected statistics, pausing interval seconds
               between each display. Press Ctrl+C to stop redisplaying
               statistics.

Thanks for detailed replay, But nw im littile confused about your issue,

What i understand is that, Very shortly  

You have a switch (4 or 8 port) and 4 PCs connected in a workgroup namely "WORKGROUP". And one of your laptop name is LRG-LAPTOP. Among these 4 PCs,  two PCs having same name.

For Your Information:
Computer name and workgroup name are diiffrent
Your workgroup name is WORKGROUP, its okey
next, You can keep any name for your computer, but it should be unique in one workgroup (Find your computer name :My computer-->right click -->Properties-->Computer Name or open command prompt--> type hostname)



Now,
 You can login all your PCs and when you are login one PC your getting event viewer error "A duplicate name has been detected on the TCP"

Thank you all for your patience.  I am trying to come to an understanding of this issue and of NetBIOS before I make any moves (I have an unfortunate history of trying out actions on computers and making a bigger mess than when I started :-)  )

At this point, from both your comments, my understanding is that this error message ("duplicate names") does not seem to be very important  as all seems to work fine even with duplicate names, and the message only seems to be on my laptop.  My options seem to be to change the name of my laptop (no big deal, I can manage that), or use nbtstat -r to purge the cache and perhaps eliminate some remnant of my recently deceased laptop that might have had the same name as my new laptop.  IS MY UNDERSTANDING CORRECT SO FAR?

My hesitation is firstly, what possible damage I could do using nbtstat -r (or any of the nbtstat switches), though probably it is fairly safe - IS THAT CORRECT?  .... and I am trying to understand how someone has set up the network here to see if there are other duplications or messy configurations that need to be cleaned up.   Would greatly appreciate one or both of you seeing me through this process.  If you think this expands my original question beyond its point value, please advise and I will open up an additional question.

ChiefIT:  Thank you for your informative posting.   I am aware of the switches for nbtstat and will experiment with them when I get all the available machines up and running - and then I will report back.  Not sure if I have a WINS server, but if I run that switch RR can I assume it will do no harm whether of not I have a WINS server?

afthab:   I have a 4 ethernet port modem/router, which also has wireless.  At no point have I had all 4 (or 5) computers accessing the net at the same time.  I will attempt that later and see what report I get with nbtstat -n, but there is another person (Kathy) involved here (in the same LAN) whose cooperation I need and that may take a few hours to arrange.  To try and answer your last posting:  There WERE 4 computers on this LAN (which is named WORKGROUP - I am just not sure the person who set this up - whne messing around with the wireless settings -  didn't somehow also set up a second network which is hidden in here somewhere).  The original four computers all had different names (an LRG  desktop and an LRG-laptop upstairs, and a Kathy desktop and Kathy Laptop downstairs) with no duplicate names.  Then the LRG-laptop fried its motherboard and has been junked, and replaced by a new LRG-laptop.  These two laptops probably were both named LRG-laptop, but the older one is junked and non-functional (so no way to check its name) and is NEVER on the net any more - so maybe I just need to purge the cache with nbtstat - r.   At the same time Kathy has gotten a new laptop, BUT her old one is still functional  and could be on the net at the same time (making possible total of 5 computers that I could get on the net, except my desktop is at the shop for repairs and not available for this test).  My laptop computer reports its name as "LRG-laptop"and that its workgroup is "WORKGROUP".  If there was a second network set up by mistake, where would its name show up?  Nothing in the my computer report, or in Network and Sharing Center.- which just reports a "private network"and then refers to my modem/router code (BigPond 0078).

I did manage to turn on Kathy's desktop last night (nighttime in Australia)- at a time when when my LRG-laptop was turned off) - and got the following report with nbtstat -n:  

C:\Users\Kathy>nbtstat -n

Local Area Connection:
Node IpAddress: [10.0.0.3] Scope Id: []

                NetBIOS Local Name Table

       Name               Type         Status
    ---------------------------------------------
    KATHY-DESKTOP  <00>  UNIQUE      Registered
    WORKGROUP      <00>  GROUP       Registered
    KATHY-DESKTOP  <20>  UNIQUE      Registered
    WORKGROUP      <1E>  GROUP       Registered
    WORKGROUP      <1D>  UNIQUE      Registered
    ..__MSBROWSE__.<01>  GROUP       Registered

ALSO- got an interesting message on Kathy-Desktop, to the effect (don't remember exact words) that "cannot access names of other computers on network because cannot access server LRG-laptop".  That confused me - I knew LRG-laptop was turned off at that time, but did not realise that LRG-Laptop was acting as a server for the network - and I still can't believe that is correct.  

When doing nbtstat -n on Kathy's laptop (Kathy-PC), got the following report (Kathy Desktop WAS on at the same time):

Local Area Connection:
Node IpAddress: [0.0.0.0] Scope Id: []

    No names in cache

Bluetooth Network Connection:
Node IpAddress: [0.0.0.0] Scope Id: []

    No names in cache

Wireless Network Connection:
Node IpAddress: [10.0.0.4] Scope Id: []

                NetBIOS Local Name Table

       Name               Type         Status
    ---------------------------------------------
    KATHY-PC       <00>  UNIQUE      Registered
    WORKGROUP      <00>  GROUP       Registered
    KATHY-PC       <20>  UNIQUE      Registered
    WORKGROUP      <1E>  GROUP       Registered


I do not understand why KATHY seems to also have duplicate names in those nbtstat reports, but she has never received a "duplicate name"error report.

I will attempt to get all computers on the network later today (except my desktop which is out at the shop for repairs) and then do a nbtstat report.  If you wait until I can generate that report and post it, perhaps that will give us all the information we need (unless you also want a "ïpconfig" report.  Do I need to do a nbtstat report  for each machine, or will the report just from my laptop give sufficient information to unravel this confusion (which is clearly my fault - arising from my inability to coherently answer your questions).

Many thanks again - I'll report back later.

OK - several hours later, and it is beginning to look like the original problem has gone away.  Yesterday kept getting the "duplicate name" error message - but today not one message, though booted up more than 5 hours ago.  

 I thought I might have solved the mystery when I remembered that LRG-laptop was connected by BOTH ethernet AND wireless at some points yesterday--- and maybe that led to "duplicate name"error... but when turned on wireless today, along with ethernet, could NOT duplicate the error message.

Just to follow up on the suggested actions:  turned on all 4 computers presently on site.  My LRG-laptop (on ethernet) could see all 4 using net view (4 different names), as could a laptop I brought from downstairs and connected via wireless.  HOWEVER, the desktop and other laptop downstairs would not respond to "net view"command - giving a "system error 71" and then going on to say computer cannot accept any more connections.  Tried a re-boot and googled the error code, but no resolution.

Since my original problem seems to have gone away, I will test it out a day or two and if the duplicate name error message  doesn't arise again will award some points (even though it seems to have resolved itself without any action).  Meanwhile if you can shed any light on the "system error 71" problem that arises on some computer in the LAN when try and use "net view", that would be most appreciated.

Addendum....

When took one of laptops off net, the System Error 71 went away and 3 remaining computers successfully responded to "net view command.- though would still like to know (maybe only for academic purposes) how to get around System Error 71 when all 4 or 5 computers on net (which is a highly unlikely scenario).

Also sometimes getting a message on computer down-stairs when use net view that cannot access computer names as cannot access LRG-laptop the "browser master".  So this message referring to LRG-laptop as Browser-master rather than as a server.  What the heck is a browser-master?  I'll google that!

All I ever wanted to know about Master Browsers, and more:

http://www.comptechdoc.org/os/windows/ntwsguide/ntwsnfinding.html

plus numerous other Exp Exch threads on it.--- but getting off topic of this thread

ChiefIT:  I greatly appreciate the time you took to try and educate me.  I get the gist of it and have saved the article you referenced to study later.

I suspect you are correct that the LRG-laptop machine got counted twice when both NIC and wireless were turned on (I was trying to replicate the "duplicate names" error).  Also I had a printer hanging off this machine and at least one of the machines downstairs had a printer and scanner hanging off it.  I doubt a hacker has cut into the network.  Have WPA code protection on wireless, and each machine has full security software (AVG 8.5 or Norton 360 or McAfee) - though maybe I'm being a but naive thinking that gives full protection.

We have NOT, to this point, shared files or printers over the local network, but that may change.  My recently deceased XP laptop had a printer and scanner that do not have drivers that will work beyond XP (Vista or Windows 7) - so when I want to print (or scan) to my new laptop I may need the local network to reach the Vista capable printer (and scanner) that usually hang off my desktop, or to reach kathy's color laser printer down-stairs.

I'll recheck the settings - I believe it is possible to turn on sharing of printers but turn off sharing of files.

Thanks again

Many thanks for helping to educate me.  If the article is not clear or additional problems arise in this area I'll post a new question