dont keep them together unless for breeding. it stresses them out and one day you can find one of them found their way into the other ones belly.

to breed, first you have to be sure one is male and one is female so you need to get them probed or popped by a vet or someone else with experience in sexing them.

you also have to be sure the female isnt too small. i dont know what the weight and length requirements are for gopher snakes to breed so i cant help you there.

i recommend you do some research on them. google's your friend.