Hello,

This is a common appearing question on this forum and various blogs however I have some differing criteria.

We occasionally see a Duplicated Computer Record created after an OSD has completed. Our OSD's always undertake a "New Computer/Bare Metal" scenario (a rebuild of that machine does not delete the Active Directory record and does not create a duplicated computer record)

Unknown Computer Support is NOT used. We Pre-Stage all our machines using the MAC Address.

Active Directory System Delta Discovery is enabled - Default 5 mins

The "Inactive" computer record has Agent Name of Manual Machine Entry with the appropriate Agent Time. Client = No

The "Active" computer record has Agent Names of MP_ClientRegistration and Heartbeat Discovery with a much more recent time

Some of the Blog Posts point towards an Unknown Computer Support scenario and AD Delta Discovery creating the record before the Setup Windows and ConfigMgr action is fully completed and registered the record. However we are using the Pre-Stage scenario.

We can remove the duplicates from a Collection Query however would like a complete answer to why it is happening

Thanks in a

Hi,

Have you tried to use both of the MAC Address and the Netbiosname in the prestage, these are two of the conditions that a new SMS Agent is checking. Please refer to following thread for details:

https://social.technet.microsoft.com/Forums/systemcenter/en-US/b86b358e-1e49-41f3-b681-7728bf7f2022/duplicate-system-entries-after-agent-installation-when-manual-entry-was-there?forum=configmgrsdk

Also you can consider to setup 3rd tier of collections to meet your request.

http://blogs.technet.com/b/cmpfekevin/archive/2013/11/21/import-computer-does-not-show-up-in-collection.aspx

How I understand it, the Client checks for the SMBIOS GUID as the preferred option of that or MAC. We are also building Tablet PCs which share USB Ethernet Adapters so that MAC Address for Pre-Stage is not viable (There is an article for this regarding a Hardware Inventory post build so the WiFi MAC is picked up, but this does not suit our processes)

We also have a well structured set of Computer Collections and finding the Computer Records is never the problem as the issue is a new record being created occasionally post Task Sequence.

Is it recommended to raise the AD Discovery Delta to 15 minutes say?

Again, we can easily remove the duplicated record but just don't want it to happen in the first place

Hi,

A design change was introduced with the release of Microsoft System Center Configuration Manager 2012 SP1 that changed the NetBIOS name property of the Active Directory discovery DDRs to no longer be a key property (as it is considered not unique enough).

This change will cause some deployment scenarios to no longer work the same way as they did with product releases before Configuration Manager 2012 SP1.

Raising AD Discovery Delta may be helpful for this issue, but the discovery may still have change to discover the machine just boot in PE. We can consider to merge or delete the duplicate records. Following blog provided s script to do it.

http://blogs.technet.com/b/configmgrteam/archive/2011/09/09/known-issue-and-workaround-duplicate-records-when-you-use-unknown-computer-support-with-active-directory-delta-discovery.aspx

Meanwhile, regarding your scenario, we just released a blog with our best practice, please check:

http://blogs.technet.com/b/configurationmgr/archive/2015/08/27/reusing-the-same-nic-for-multiple-pxe-initiated-deployments-in-system-center-configuration-manger-osd.aspx