On 14 Jun 2012, Calvin Morrison stated:
It seems to make sense to only use /lib64 or lib32 when that is not the native arch. ( you wouldn't say /bin32 if you're on a 32 bit system)
Debian (and I) agree with you. RH et al do not :(
(though binaries are a different matter. You very rarely have two versions of the same binary, one 32-bit and one 64-bit, so one directory will suffice in any case. This situation is downright common with libraries, so two directories are essential.)