Views:
The issue is an expected behavior because: 
  • The VM is reverted, so the agent did not have a chance to unregister its record. Therefore, the WFBS server will keep the agent's record. If the record does not show an Online status within 30 days, the record will be removed from the database.
  • When you reinstall the client after reverting the VM, it will report back to the server.
  • Since the GUID is different, the server side would display two records.