How does Sync Center know which version of a file to keep?
Sync Center looks to see if a file has changed and then copies the updated version to the other location to keep both locations in sync. Most sync partnerships have Sync Center keep the most recent version of a file and overwrite the older version. Sometimes, Sync Center will prompt you to choose which version of a file to keep. This usually occurs when a file has changed in both locations since the last sync. When this happens, Sync Center will notify you of a sync conflict, which you must resolve before it can sync the items in conflict.