No. It means that Game Center will let test builds play matches against any version of your app (test or otherwise).
It means you can test easily because you can create games against anyone, but there is an opposite problem when you're doing work on an update: When you try to test automatic matchmaking, Game Center will match you up against any of your existing users. If you've changed the communication protocol for your update, or have bugs in your update, or have added new features in your update which are incompatible with old versions of your app, then you will not be prevented from connecting with them. At best, you will cause communication errors with the customers you accidentally connect with - possibly crashes if your net code is not so robust.
To avoid it, after release you have to be very careful about testing multiplayer. Using direct invites rather than auto-matchmaking, or using Player Groups (playerGroup in match request) to avoid accidentally connecting with existing customers.
Player groups is the way to go. Thank you Columbo, I've been searching for an answer to this problem for a while...