Parent elements have a reduced set of data to compare during the merge process. If an MTF (Mib Translation File) changes on a parent element and no entry exists in the $NH_HOME/poller/mtfMigration.rules file, a duplicate element will be created for the parent element.
Example mtfMigration rule:
The "oldMtf" would be the existing MTF, the "newMtf" would be the MTF of the newly discovered element.
Please open an issue with CA Technical Support if this is seen.