I had problems syncing, tried multiple times over the last few days and finally got a good sync. I now have hundreds of new duplicates created by the sync process in my Ancestry online tree. I am going through each one, one by one, trying to ID which is the good one and which is really a duplicate. It did not duplicate them completely, so some of the dup0licates have media, others don't.
Sometimes all the children and parents in a cluster are duplicated, so I can flag a bunch pretty easily by putting each up on my dual monitors side-by-side. In other cases, the duplicate person is mixed up with good folks, so I have to unlink/relink parents/children, spouses, etc.
I had cleaned up the previous duplicates generated by the FTM sync not too recently, so know that I did not create this mess myself.
I sure hope the programmers get FTM to work properly.