Add them as a Straight Pool Deluxe opponent, not as a local player, and every game between you shows up on both iPads.
Connect with an opponentSend a request with the + SPD button. You can play them right away; once they accept, your games together appear on both iPads.
Already added them by hand?If you typed in a player who turns out to have Straight Pool Deluxe, here's how to get your games onto both iPads from now on.