I'll just add my $0.02 and say that working at an LFS that sells exotics, as well as meeting LOTS of reptile keepers from noobs to people with 25+ years has taught me one important thing: There's not always only ONE way to keep reptiles successfully. Just because it works for you doesn't mean it will work for someone else, and vice versa. That doesn't mean you shouldn't research the hell out of everything you can, and to be honest I personally wouldn't keep two ball pythons together, but I know people (not to mention a zookeper) who have done it successfully for many years, and to my thinking if over the course of 3 to 5 years no major health problems arise as a result, then I would feel a little foolish arguing that they really are stressing each other out and they will someday end up dominating (or eating?) one another. It may be true in most cases, but I just dont think you can say with certainty that under the proper conditions snakes CAN'T be kept together. That said, I would leave it to experienced hobbyists and professionals who would be constantly alert for any behavioral change that could indicate compatibility issues. But really I don't see the need to get so up-in-arms about it, on either side of the debate. Reptile people have a habit, I've noticed, of thinking their way of doing things is "THE way" but I think this can be detrimental for the hobby as a whole.