Well, even though Debian supports this I rarely see it used to install multiple so's side-by-side. Fedora will let you do it, but the entire development process tries to avoid compat libraries where possible (you are supposed to send a message out to the mailing list if a package you maintain is getting a soname bump so others that depend on it can rebuild during the rawhide cycle, this stops being an issue once Beta hits since versions get locked down).