Maybe you have seen duplicated MAC Addresses in your SCCM environment. When you want to deploy something to a device, there will be a problem because SCCM don’t now with object he needs to apply.
There are two queries to find duplicated MAC addresses:
Find by MAC address
select distinct * from SMS_R_System where SMS_R_System.MACAddresses = “aa:00:bb:11:cc:22”
Find by UUID
select * from SMS_R_System where SMS_R_System.SMBIOSGUID = “AAAAAAAA-1234-BBBB-5678-901234CDEFGH“