Duplicate items in chest

While in a Survival LAN game. I used my iPad Air, iPhone 6s+, and my Win 10 PC (using Win 10 Beta Edition) all at the same time. I also used my iPhone and iPad only at the same time with the same results. I also used an iPad Air, iPad 2, and my iPhone together. Everyone look in the chest. Anyone can place an place an item in the chest. Everyone sees the item. Have the iPad AIR character remove the item FIRST! The item will not disappear for the others. Everyone else can remove the item. Repeat until you have the desired number of items. I duplicated diamonds, string, enchanted fishing pole, and gold successfully.