Duplicate Records when you use Unknown Computer Support along with AD Delta Discovery

I've run into this scenario a couple of times after enabling Delta Discovery and have got into the habit of doing a manual sweep for duplicate records, or extending the Delta Discovery period, but that kind of defeats much of the reason for it.

http://blogs.technet.com/b/configmgrteam/archive/2011/08/17/known-issue-and-workaround-duplicate-records-when-you-use-unknown-computer-support-with-active-directory-delta-discovery.aspx

Basically, if you have Delta Discovery enabled and then image a new device using unknown computer support SCCM creates a record for the new device, but then if Delta Discovery runs before the Task Sequence installs the Client Agent and after the OS has been joined to the domain, 2 records will be created within SCCM.  The problems start though when SCCM can't link/merge the two together and won't age either of the out of the database either.

Two choices are then left for you.

1. Manually sweep for duplicate records and delete the one that shows no client installed.


2. Setup a status filter rule that will run a script to automatically delete the record.

Thanks to the TechNet article posted by Minfang Lv, this is now relatively simple to do, with the scripts and instructions supplied.

As always, test before putting straight into production.