I've been trying and haven't noticed any dupes. How have you been doing that?
I was just removing duplicate items as usual. It may be related to gallery size, or the number of items the gallery contains - I have a size 250 gallery, with 1200 or so unique items.
Thats why I ran into the issue - I was removing the extras, since I only want 1 of each item in it, and lost track of a few.