Same room is fine if you get the boa from a reputable breeder, IBD is only transferred via some type of contact as far as anyone can tell, however paramyxo is airborne. If you get it from a great trusted reputable breeder the chances of that is slim.

And I believe any boid/boa species can carry both without symptoms for a very long time, and Dumeril's boas included. Someone correct me if I'm wrong...