The KDC encountered duplicate names

StBenet used Ask the Experts™
We are getting the following error " event ID 11 The KDC encountered duplicate names while processing a Kerberos authentication request" on our DC (see attached text file).  I've found the duplicate entry using "setspn -X" (see attached jpeg) however the duplicate entry is a user "Administrator" and not a computer.  I can use "setspn -D" to delete the entry but I'm unsure what the SPN and computer name would be.  I've never had to do this before and I don't know what the consequences are if I get it wrong. Can anyone help please.

Thank you in advance. MAGPIE-ERROR.txt Duplicate entry screenshot
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I'd check to see if you SQL Service is running as LocalSystem or as the Administrator account (check the Log On As tab of the SQL service).  If SQL is running as LocalSystem, then we want to keep the SPN on CN=Magpie.  If SQL is running as Administrator, then we want to keep the SPN on CN=Administrator.

Assuming SQL is running as LocalSystem and we want to delete the SPN from Administrator, we would use:
setspn -d mssqlsvc/magpie.sbbcx.local:1433 administrator

If we decide we need to take the SPN away from CN=Magpie, then the syntax is actually:
setspn -d mssqlsvc/magpie.sbbcx.local:1433 magpie$
Note the $ on the end of the computer account name

If we pick the wrong one then some applications may not be able to connect to SQL but we can always use "setspn -a mssqlsvc/magpie.sbbcx.local:1433 <accountname>" to put it back.


Deleted CN=Administrator without any problems.  Many thanks, your explanation was excellent. The $ on the end of the computer name is one to remember, haven't seen that mentioned on any other sites.

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