I have experienced a similar thing on realms. If you have two llamas in a boat and player 1 sits onto llama 1. A player put something in llama 2 inventory. Second player open the llama 2 inventory by shift right click. Player 1 logs out. At this time the player one, the llamas and the boat disappears but the inventory GUI is still open and player 2 can take things out of it and then close the GUI. Then when player 1 logs in again the things are still in llama 2 inventory and there are now tow sets of identical items.
MrDfly75
I have experienced a similar thing on realms. If you have two llamas in a boat and player 1 sits onto llama 1. A player put something in llama 2 inventory. Second player open the llama 2 inventory by shift right click. Player 1 logs out. At this time the player one, the llamas and the boat disappears but the inventory GUI is still open and player 2 can take things out of it and then close the GUI. Then when player 1 logs in again the things are still in llama 2 inventory and there are now tow sets of identical items.