[boost] [config] Why don't 32-bit and 64-bit Windows DLL's have different names?

A C++ committee library working group member just asked me why Boost 32-bit and 64-bit Windows DLL's don't have different names. I couldn't remember; could someone please explain? --Beman PS: http://www.boost.org/development/separate_compilation.html is looking a bit dated due to the references to older VC++ versions. Perhaps someone could do a pass through it adding more modern references.