Issue : you will see that a computer dissapears and appears in the windows update server (wsus) or only one of the two computers appear .
Cause : Using a cloned system without doing a sysprep leads to creation of duplicate SID’s
* Open Regedit
* Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate In the details pane of Registry Editor,
* Delete the following registry entries: PingID AccountDomainSid SusClientId SusClientIDValidation
* Open command prompt and type without qoutes
1. wuauclt.exe /resetauthorization / detectnow
2. Wuauclt.exe /detectnow
NOTE : Do this on all computers with duplicate sus id’s to fix the issue.