I've just started allowing MDT to join computer names to AD. Prior to this, we have always manually added the name after verifying it doesn't already exist. If you try, AD will bark and say it is already there.
I manually created a computer name on one OU, then had MDT create the same computer name in a different OU.
What I saw was...no computer added in the new OU but rather the pc assumed it was the one in the other OU.
Rather than have someone forget to check names and we are bumping devices off the domain, how can MDT check if a name exists in any OU we have? I don't have a DB set up. Just adding computers manually or, for my testing purposes, having MDT create a name I know isn't there. It works, provided you check. So, if there is a way, I'd be interested in giving it a go.