To be honest with you, it's not even good to do with ball pythons. Snakes are not communal creatures in general and will get stressed out if they are stuck in an enclosure with another snake. Another thing to consider is that when you house two snakes together, if one of them is sick then the other one is almost bound to get the same thing. And boas have a much lower tolerance than balls and a much higher prey drive, which could lead to "accidents" especially if one boa is smaller than the other. Boas have been known to try to eat other snakes if they're kept together and they think they're big enough to.
TL;DR: it's not good to house any snakes together unless it's temporary for breeding purposes.