Brb and balls require quite different requirements. Balls need a hot side of well over 90, where a Brb could be killed with temps even close to that. Brb also need humidity of 70-80% compared to balls needing 60-70%. And putting a red-tailed rat snake in that enclosure would be a terrible idea. They are a very arboreal species that gets large and loves to climb.

You really should move one of your snakes you currently have into it. Both corns and balls need more than a 2x2 space when full grown IMO. I'm really not trying to come off as if I'm harping on you, just trying to help you make a decision that's beneficial to the needs of your snakes.