Here're the instructions on how to use it:
1 - Equip any set of arrows.
2 - Draw your bow back and press B while its drawn.
3 - Highlight above arrows and press A once.
4 - Find any item you wish to clone and drop it.
5 - Exit and Profit.
Here're the rules that the glitch seems to follow:
1 - The game will drop your selected item X amount of times, where X is equal to the number of arrows in your selected Arrow Set.
2 - It will drop the item(s) in your inventory first, and then drop clones until the total amount dropped is equal to your arrow count.
Ex: You have 5 arrows and 1 club, and want to clone some clubs . You do your little trick, and out pops 5 clubs. The first club is the original club from your inventory, and the other 4 are the clones. Making a total of 5 clubs, as your arrow count.
3 - If the item to be cloned is one of multiple, and totals less than your arrow count, then the game will drop X items in stacks of Y (where Y is the amount of items in your original stack) but fractionize the last stack in order to not go over X.
Ex: You have 5 arrows and 3 clubs. Clone Time. You end up with two stacks of clubs. One stack of 3, and another of 2. (3+2=5) ... or ... You have 5 arrows and 2 clubs. Clone Time. You end up with 3 stacks of clubs. Two stacks of 2, and another of 1. (2+2+1=5)
4 - If the item to be cloned is one of multiple, and totals more than your arrow count, then the game will drop X items, and since it drops legal items first, it will have no need to drop clones because Y is greater than or equal to X.
Ex: You have 5 arrows and 6 clubs. Clone Time. You end up with one stack of 5 clubs and 1 club in your inventory. You didn't clone any clubs because you had the same amount or more clubs than arrows.
5 - According to the lists of items that can be duplicated, and from my own assumptions, the glitch only works with items that have an infinite nature. Anything that can respawn (whether by restocking in stores, or plants growing them, or chests spawning more), chances are, they can can be cloned. On the other hand, if the item has a proper name, is enchanted, or is a quest/plot item you won't be able to clone it.
Notes: I don't intend this to be a perfect interpretation of the glitch, but it's what i understand of it. And to be sure noone thinks otherwise, it was Grimwrecker that found this glitch. I didn't, i merely refined it