Core Issue
The replication failed [Subscriber= x.x.x.x] Duplicate server found, don't process error message appears when a duplicate server name entry exists in the SQL Server Database.
Resolution
In order to resolve this issue, check the Process Configuration Table in the SQL Server Database and remove this duplicate entry and rerun the UA Utility.
Refer to When the Upgrade Assistant is run for a Cisco CallManager upgrade from 4.0.2 to 4.1.3, the replication failed,replication job not found error is logged in the Upgrade Assistant log for more information related to Upgrade Assistant Utility Errors.