When ratings are manually added or imported into The Raiser's Edge that also exist in ResearchPoint they are not connected. So the sync from ResearchPoint doesn't recognize them as being the same because they were not added by the sync. This causes the sync to re-add them as new ratings.

To resolve this issue we recommend running a global change process as described in How to globally delete prospect ratings.  

Once the ratings are added by the sync, syncing the record multiple times will not cause duplicate ratings.