Super Gamer Dude
This cheat duplicates items in a similar way to the pre patch method using a bow and arrows. I have seen variations on this method involving swinging weapons/fists but found they did not work (on the PC at least). This method works with Shivering Isles installed and is more straight forward than the old method.
To start with you will need at least 2 identical scrolls. Open you inventory and equipment them. Click on the scrolls once more, then drop the item you would like to duplicate. The quantity of the item needs to be less than the number of scrolls, for example if you have 10 scrolls the number of items duplicated at one time has to be 9 or less. Exit your inventory screen and the duplicates will fall to the ground. The number of items duplicated will be equal to the number of scrolls. To repeat this go back into the inventory screen and click on the equipped scrolls and drop the item to be duplicated (no need to unequip and equip the scrolls)
This method does not duplicate stolen items and some rare/quest items. It is however useful for duplicating light, valuable items such as gemstones which can be sold.