Each interface board is equipped with a small magnet next to a hal sensor. In theory, an interface board should only activate, when it detects the magnetic field of an other interface board, so an other module’s side. There are other circuit protection practices in place as well, so the module should be protected from the case you wrote.
But, as with all consumer electronic products, it’s better safe than sorry. A bit of tape on the unused side might be handy, just as you wrote.