[CentOS] multilib error on centos 6.2 x86_64

I just tried to update to CentOS 6.2, but I am faced with "Errors: Protected multilib versions" error, the offending packages are:

jasper-libs.i686
krb5-libs.i686
nss.i686

After some investigation, it turns out that there are newer packages in "x86_64 updates" repository, but only for x86_64 version, while in "x86_64 main" repository there are older i686 version packages, causing version conflict. To solve these problem, I have to manually install the newer i686 packages in "i686 updates" repository. Is there anything wrong in the build system that lacked those i686 packages in"x86_64 updates" repository?