Simply put, I've been getting nothing but duplicate exotics after dropping then completing the Strum Exotic quest. One of the quest steps was to collect an Exotic engram, which I had done, then do some mission on Nessus. I (stupidly) decied I didn't want to complete the quest and dropped it. After that I've been getting Wormgod Caress arms almost exclusively from world drops and Xurs engrams. I've since finished the quest and got strum, but when I purcahsed an engram from Xur he gave me Synthoceps, which I already have. My exotic collection inst complete at all, I still have plenty of weapons and armor to collect from warmind and curse.