You must ask to Centos, why they are install 64bit and 32bit on 64bit system.
Sadly, other repos only have 64bit version for 64bit system and it's make conflict.
So, you must remove .i386 before update mysql.
In my experience, it's safe if all .i386 remove with 'yum remove *.i386' before fresh install of Kloxo-MR.