Definitely best to keep them seperate. Cannibalism is rare, but it happens, and sharing a space like that stresses out any snake. They're solitary creatures and compete for the "best" spaces, and dominate each other. Plus if one gets sick, they both get sick.

I used this DIY Plastic Housing tutorial to set up Gomez's enclosure, cheap and excellent for shedding and such. He's a happy little dude in there. Doesn't take up a lot of space either, BPs are pretty laid back and don't need a whole lot of room. Hope that helps!