When importing Policy Store export from old R12.0 environment to new R12.52 SP1 environment, the XPSImport validation step is returning the following error:
(WARN) : [sm-xpsxps-03220] CA.SM::Realm@06-0e9046e2-864a-105a-98a3-84d3c46c002a(MyRealm): Duplicate value for CA.SM::Realm.Name="My Realm": CA.SM::Realm@06-0e9046e2-864a-105a-98a3-84d3c46c002a(MyRealm),CA.SM::Realm@06-4ab90e77-7714-103c-a18d-84d3c46c002c(myrealm).
Those warning messages appear to inform that during the import the referenced objects were found to have the same name, and letting you to be aware of it just in case an object duplicity has been detected.
These objects should be reviewed individually to check if they could be duplicated, or just having the same name, so you can modify it prior to the upgrade if needed. In the warning message, it is included the XID of both objects, and the current name.
To illustrate that according to the sample given, running XPSExplorer, you need to modify the real name to be different each other :