Cause: Sysprep should have been selected to regenerate the SID, but in the hard drive to the copy process, the disk reboot inadvertently make the mirror system boot, so that some of the client Sid the same.
(Note: The error here should be caused by the same susclientid, so the following solution is to delete and reactivate the build Susclientid.) In fact, Sysprep modifies the computer SID, and in my case, the SID of 2 computers is indeed different, but Susclientid is the same.
To view the computer SID method, you can go to the Microsoft website download sysinternal psgetsid tools: http://technet.microsoft.com/en-us/sysinternals/bb897417.aspx)
Is like: Other to now have not found anything, is in WSUS 3.0 SP1 console, see the client, sometimes to Taiwan A, sometimes to Taiwan B, there is a no B, there is b no A, can only show one.
Solution: All operating on the client,
net stop Wuauserv
Delete the hkey_local_machine\software\microsoft\windows\currentversion\windowsupdate below Susclientid and Susclientidvalidation Key
Remove the SoftwareDistribution directory below%windir%
net start wuauserv
Run wuauclt.exe/detectnow/resetauthorization command
Fast, in the console you can see the new joined the client!