DHCP filling up with IP's that are not pingable

Can you get MAC addresses on whatever is filing up the DHCP range?
what does a traceroute show?

Using PowerShell...

Enable conflict resolution

Set-DhcpServerSetting -ConflictDetectionAttempts 2

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Delete these bad entries

$DHCPServer = "YourServer"
$DHCPBadReservations = Get-DhcpServerv4Scope -ComputerName $DHCPServer | Get-DhcpServerv4Lease -ComputerName $DHCPServer | Where-Object -FilterScript {$_.HostName -eq 'BAD_ADDRESS'}
$DHCPBadReservations | Remove-DhcpServerv4Reservation -ComputerName $DHCPServer

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BAD_ADDRESS entries result from non-allocated IPs answering a ping when tried to give out to DHCP requests. This can happen if removed prematurely from DHCP, or set up statically.

I've never seen DHCP entries with the IP address as host name. That looks like some device (e.g. a switch) going wild. Is there a DHCP relay configured (on a router or L3 switch)?

Yes, that is why I recommend enabling conflict resolution. Was just in a rush so didn't expand on the "why"

I cannot get MAC Address's of the IP's with the IP as the host name, they look like this (see attached) They are also not pingable. I was able to sort out the bad address issue, I had forgotten about a few static IP's. But still have an issue with the IP as the hostname being shown in use and not pingable. I can delete them and they will not return, until i do a reconcile, then they return. I already have conflict detection set to 2.

I found this about the same symptom: https://community.spiceworks.com/topic/332169-dhcp-showing-ip-address-as-name-field-on-address-leases

My bet is on switches which are not properly configured, building a loop / mirror, e.g. with aggregated ports (aka LAG, LACP, Etherchannel, Bonding, ...).
The strange in above thread is that they blame Kaspersky AV, but the KB article is no longer there, as it seems.

There could also be some virtuell NIC causing this - TAP adapters (used for e.g. OpenVPN and some Linux add-on routing/ethernet features).
The long ID, btw, is the ASCII representation of the IP address. 0x31 30 2e = 10., aso.

"I cannot get MAC Address's of the IP's with the IP as the host name" can you do a "show arp" on your switch?

I agree with the folks above it is most likely a loop or a physical or virtual NIC that is sending requests for DHCP but unable to correctly reply.  

You might want to check your VLANs and helper address configurations.