Something I noticed when i took my glass armour off of a mannequin to improve it (mannequin in hjerim), was that the armour spawned back onto it when i got back into the house. I then tried it with another armour set to make sure that it could be replicated, and it respawned three out of 5 of the pieces of armour (Out of armor, boots, gauntlets, helmet, and shield, only armor, boots, and gauntlets were duplicated.) I just did it a third time and again, boots, armor, and gauntlets were spawned back in. Anyone else try it to make sure it just isn't my game?
Edit- Preemptive edit, yes, i have the latest patch.

I tried in honeyside...and nothing

Try in Hjerim? That's the only place it happened for me.