Shipwreck loot duplicated on destroying chest

I was looting a shipwreck, specifically the chest through the door. I encountered a delay in opening the chest (~5 seconds) but was able to open it and loot the treasure, emptying the chest. I then stepped back into the doorway to gain air, before attempting to destroy the chest to take that as well, but on destroying the chest, all the original loot poured out as if I had never looted it to begin with.

Inventory shows duplicated set of loot including armor trim and empty treasure map.