I restored files onto my new computer using Time Machine (from my old computer). I manually restored specific files and folders. The user name was the same on the old MacBook Pro and the new MacBook Pro. Now some files have the same user name listed twice in the Inspector! It causes problems, such as being unable to properly compress these files (and directories). Here's a screenshot of an example:
I've tried using "chown" in Terminal. I can add another user this way, but it doesn't solve the problem (and isn't recursive meaning it would take forever to do properly).