I'm sorry to hear your experience with Spanning Sync hasn't met your expectations, and I want to find and fix whatever problem you've encountered. I don't see any support emails from you, so please get in touch with me directly at charlie.wood@spanningsync.com.
I'm sorry you're having trouble with Spanning Sync. Several other customers who use The Missing Sync have reported problems with duplicates, and we suspect some sort of incompatibility between us and them. We'll be working directly with Mark/Space and hope to find a fix the problem soon.