I've noticed that it happens after fast traveling somewhere.

@omnistrife99 Just tested and can confirm that it works. Let's hope it'll stay collected.

I don't know how, but I acquired the Huntsman Armor torso, I noticed after loading first thing today. Later I opened a chest that had the armor piece, which I assume is the intended way to get it, and now I have two of them. In addition, I tried upgrading it in my inventory, and when I equipped it, and then equipped the non upgraded one, it duplicated the level 1 upgraded one. So now I have 3 Huntsman Torso armors in my inventory. I'm on PC.

I have the exact same problem. Furthermoing these bugged items is also problematic, as it would randomly revert. Hope that upgrading them at the blacksmith will solve this.