I have 94 bloods (at the moment), and the only time 2 are in 1 cage is when they're being bred. 1 snake per cage is a very good rule to follow regardless of species. You would need to house the new snake separately anyway for quarantine, so why even bother putting them together in the long run? If you keep 2 snakes in one enclosure & there's a problem - i.e. regurge, abnormal feces, etc, how will you pinpoint which snake has the problem? And if there is something wrong with one snake, you're making the second one vulnerable to the same problem by keeping them together. 2 snakes sharing a water bowl is a great way to transmit pathogens from one animal to another.
And, hypotheticallly speaking of course, if you're wanting to keep 2 snakes together for lack of resources with which to get a second enclosure, don't get a second snake.
All food for thought...
K