Yum is a very handy tool, but sometimes with several repos going on you can mess your system.

When you get a lot of duplicated rpm's packages you can get rid of them with this comand (you can add --nodeps switch but i don't advise) 

for RPM in `rpm -qa --qf '%{name} \n' | sort | uniq -d`;do rpm -e `rpm -q $RPM | head -n 1`;done

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