When Items get put into a chest and the game crashes and the world is loaded again, the items in the chest appear in the player's inventory and there will be duplicates of those items in the chest. 

In my survival world i put items in a chest and did something else and the game randomly crashed. I then launched the game and went back to my world and saw the same items were in my inventory but then i opened the chest and saw duplicates of those items in there.