Dont happen ever time but this is how it works. Get on mount and load your inventory with non stackable items. Now Relog and you will no longer be on your mount and you will find your mount in inventory. Now Place or delete an item from your bags and relog. When you look you will see you bag is full again and some time item will be x2 that was not there before. If it is a unique its stats will x2. It works but with the long relog in time take time to get the resualts. I have not figured out what bag slot gets deleted yet but the item deleted will reappear after relog.