I will play with that possibility again. My experience is that the Merge All Duplicate Citations tool ignores media attachments when making its Merge or Don’t Merge decisions. That’s a problem for media downloaded by TreeShare for certain strangely indexed Ancestry collections where the only difference between “different” citations is the media file itself. I hope that problem is solved in the newest RM9. The Merge All Duplicate Citations tool really should take attached media files into account. If that problem has been fixed, then it would be a possible explanation for the strange behavior that I saw.