We never deactivated either, and have over 30. But then we had one of those "Magic Band" problem trips, nothing would work, no bands would open doors, Guest Relations checked the door itself and swore it wasn't them, and we got told, as many others, that we have too many MBs active and it's somehow screwing up the system. As others have mentioned, the veracity of this claim is up for debate. But for the sake of ease I now only activate the ones I'm using on a particular trip, and no problems since. It's annoying, but not the end of the world.
But having said that, OP, assuming you have just two or three MBs each? I wouldn't worry about it. But you can deactivate the old ones if you want to. Your call.