Go to the inventory screen and equip any Scroll that you have multiple copies of (for example, five Superior Convalescence). Once the Scrolls have been equipped, press [Space] again while still in the inventory screen. Then, drop the item you want to duplicate (for example, Grand Soul Gem). You will now have the same number of that item as you do Scrolls. Note: You must have less items than Scrolls or this trick will not work.