https://bugzilla.redhat.com/show_bug.cgi?id=965914
--- Comment #9 from Dan HorĂ¡k dan@danny.cz --- http://fedoraproject.org/wiki/Packaging:Conflicts http://fedoraproject.org/wiki/PackagingDrafts/MultilibTricks http://fedoraproject.org/wiki/Packaging:Guidelines#Multilib_Exempt_Locations
It's a natural feature of multilib system that the devel packages don't conflict, the goal is to have both 32 and 64 bit packages installed. You can find many examples in the existing packages that solve this problem with modified foo-config script, a wrapper over 32/64 bit headers etc.