yum update package conflict error

Issue

• yum update error, package conflict:

rhel5-mrepo-ALL/filelists_db                                    | 5.8 MB     00:00     
rhel5-mrepo-updates/filelists_db                                | 3.8 MB     00:00     
--> Finished Dependency Resolution
Error: Package: python-simplejson-2.0.9-8.el5.x86_64 (rhel5-mrepo-ALL)  
           Requires: python(abi) = 2.4
           Removing: python-2.6.6-36.el6.x86_64 (@rhel-6)
               python(abi) = 2.6
           Updated By: python-2.6.6-64.el6.x86_64 (rhel-mrepo-update)
               python(abi) = 2.6
           Available: python-2.4.3-44.el5.x86_64 (rhel5-mrepo-ALL)
               python(abi) = 2.4
           Available: python-2.4.3-56.el5.x86_64 (rhel5-mrepo-ALL)
               python(abi) = 2.4
Error: Package: 1:perl-Archive-Tar-1.39.1-1.el5_5.2.noarch (rhel5-mrepo-ALL)
           Requires: perl(:MODULE_COMPAT_5.8.8)
           Available: 4:perl-5.8.8-32.el5_6.3.x86_64 (rhel5-mrepo-ALL)
               perl(:MODULE_COMPAT_5.8.8)
           Available: 4:perl-5.8.8-43.el5_11.x86_64 (rhel5-mrepo-ALL)
               perl(:MODULE_COMPAT_5.8.8)
           Removing: 4:perl-5.10.1-129.el6.x86_64 (@rhel-6)
               Not found
           Updated By: 4:perl-5.10.1-141.el6_7.1.x86_64 (rhel-mrepo-update)
               Not found
:
Transaction Check Error:
  file /etc/pki/nssdb/cert8.db conflicts between attempted installs of nss-3.21.0-6.el5_11.x86_64 and nss-3.21.0-0.3.el6_7.i686 
  file /etc/pki/nssdb/key3.db conflicts between attempted installs of nss-3.21.0-6.el5_11.x86_64 and nss-3.21.0-0.3.el6_7.i686
  file /etc/pki/nssdb/secmod.db conflicts between attempted installs of nss-3.21.0-6.el5_11.x86_64 and nss-3.21.0-0.3.el6_7.i686
  file /usr/lib64/libnssdbm3.so conflicts between attempted installs of nss-3.21.0-6.el5_11.x86_64 and nss-softokn-3.14.3-23.el6_7.x86_64
  file /usr/lib64/libnssutil3.so conflicts between attempted installs of nss-3.21.0-6.el5_11.x86_64 and nss-util-3.21.0-0.3.el6_7.x86_64
  file /usr/lib64/libsoftokn3.so conflicts between attempted installs of nss-3.21.0-6.el5_11.x86_64 and nss-softokn-3.14.3-23.el6_7.x86_64
  file /usr/lib64/nss/unsupported-tools/shlibsign conflicts between attempted installs of nss-3.21.0-6.el5_11.x86_64 and nss-softokn-3.14.3-23.el6_7.x86_64
  file /usr/lib64/libfreebl3.so conflicts between attempted installs of nss-softokn-freebl-3.14.3-23.el6_7.x86_64 and nss-3.21.0-6.el5_11.x86_64