Event Message:

The servers computer name and computer name both claim to be an NT Domain Controller for the name domain. One of the servers should be removed from the domain because the servers have different security identifiers (SID).

Source

Event Log

Event ID

Event Type

NetLogon

System

5511

Error

Explanation:

This can happen if identically named domains on different networks are placed on the same network.

User Action:

Remove one of the servers from the domain.