I don't have a boanded pair, but in general they can have 1/4 cup of Tomithy based pellets per 5lbs of bun, and unlimited Timothy hay as well.
To help prevent them from stealing eachother's pellets, maybe get them each their own Slim Cat balls? That way they would each have to work on their own balls to get the pellets out, instead of one of them devouring both bowls as fast as possible LOL.