i'd like to, but I have no history of the yum error outputs.. so I cannot reproduce anything, regretfully.
on this box I have quite some other repos installed for contribs and php versions, so probably there were some libraries elsewhere that were newer than those in sme repos..
anyway the problem was related to i686 and x86_64 libraries being updated to different versions, so yum would warn me and stop.
I solved by updating _only_ the conflicting libraries, both architectures at the same time, like
yum update lib.i686 lib.x86_64
so yum could choose which newer available versions were identical (multilib must be of same version number).
ciao buona befana!