The tickets aren't personalized (some regular monthly passes for public transport are/were though), so you should be fine. Since they aren't personalized and there is no way to check who the owner actually is, I would even expect them to be transferable.

Edit: looks like I was wrong -> see replies. You can also search for "9-Euro-Ticket übertragbar" (übertragbar = transferable) yourself to get a number of different German sources for that.