You should seperate them. If you choses not to then you will have to pay the price if one of the snakes do not thrive like it should, or if one gets sick you have 2 vet bills. A 55 gal tank is TOO BIG even for an adult ball python. Typical pet store employee selling things. You will get much better advice on this website than at a pet store. If you refuse to do what's best for your snakes then atleast get something to make a partition and make the 55 tank into 2 tanks. If you wont do that then both snakes need to be moved to rubbermaid tubs for feeding. Wait at least 30 minutes after feeding to move the snakes back to the 55 tank. Feeding one in the tank will create a sence of dominance in one snake over the other. This will eventually happen anyway unless you seperate them. Good luck.