RTB and BPs have differences in care requirements. They are subtle, but there, nonetheless. This is irresponsible on the part of the petstore.
If the snakes are being kept in the right requirements, are being kept healthy, and are given plenty of floor space, I don't exactly have a problem with pet stores keeping them in one enclosure. The need for space is an understandable issue, and even excellent petstores who know what they're doing will sometimes put multiple babies in one enclosure.
That said, I DON'T believe there is ANY excuse for keeping two different species with different requirements in the same enclosure.
SIDE NOTE: I also think that individual keepers should house their snakes separately... if an individual doesn't have the space to provide separate cages for their animals, they shouldn't have those animals.