Yes they will. Rabbits are very clean animals. They will share the same litter box as long as it is big enough to hold both of them. Although some rabbits can be more dominate and will try to claim the litter box as their own. In that case, you may have to use 2 litter pans.
Rabbits that are spayed and neutered are easier to litter train. Rabbits will share a litter box as long as the box is big enough for both rabbits and kept clean daily. Sometimes one rabbit will be more dominant and want to claim the box for themselves. If it doesn't accept another rabbit another box may be necessary.