Item duplication from hotbar in survival mode

Items in hotbar can be duplicated if at least two items of the same or other type are in the inventory too.

Steps to reproduce:

• collect 2 items of same kind
• long-click on the next empty hotbar-element right of the items as you would do to throw away an item.
• a number of elements equal to the rounded up half of the rightmost item in the hotbar will be dropped right in front of you and can be collected.