This glitch allows you to duplicate items by using scrolls:

Step 1: Go to your inventory.
Step 2: Equip any scroll that you have multiple copies of (ex. 5 "Superior Convalescence").
Step 3: Once the scrolls have been equipped, press A again while still in the inventory.
Step 4: Drop the item you wish to duplicate (ex. Grand Soul Gem) - you must have less items than scrolls or it doesn't work.

You will now have the same number of items(ex. Grand Soul Gems) as you have scrolls!