In a game earlier I had purchased 4 mana potions by mistake(meant to only get 3). The first 3 were in my F2 slot while the fourth one was in my F3 slot. When I needed to use a mana potion I used my F3 one first because I wanted to open up the slot for another item. However, one of the potions from the F2 slot was used. Everytime I used the potion from the F3 slot another potion from the F2 slot was used(while leaving the F3 potion there).