A 50 gallon for two beardies is nowhere near big enough if we're just talking about size alone. A single bearded dragon needs a minimum of 40 gallons to itself so 10 extra gallons for another 2 foot of beardie will not work and would be very cramped. That being said, you do not want to put two beardies together. Ever. Sure, some people do it and have no problems. The vast majority will either have fights or one dragon will be twice the size of the other due to domination issues. If you want two beardies, get two enclosures. Just because a few people have gotten away with it (which is really what I'd consider it, since there is always the chance of fighting even between established tankmates) does not make it okay or healthy for the animal. I should add that even if you got two females, they will fight the same as any male-male pair would.