okay, i was going to leave it to someone else but.... i'll list all the reasons that i remember at the moment! but i always leave something out sooo.... here goes!
1~ snakes are solitary animals by nature. when you look in and see them 'cuddling' with eachther, the one on top is actually dominating the other!
2~ if one get sick, both get sick! that means double the vet bills!
3~ if you feed both in the enclosure, this will obviously cause problems
4~ there is always the off chance of cannibalism. it's not very common but it does happen! i wouldn't want to take that chance!
5~ balls are very picky eaters. especially if they're stressed out, which sharing an enclosure will most likely do
i used to house my babies together (before i became a regular here) and these guys clued me in! and i must say, i noticed a change in both their behaviors almost immediately! they also both started growing noticeably faster! hope this helps!