I have a cheat for this game.

Items you'll need:

1. A potion(in your belt)

2. the item to be duped

Duping Items:

First: Put the item to be duped on the ground.

Second: Take a few steps back.

Third: Put a potion in your belt

Forth: Click on the item you want to be duped.

Fifth: When you're about to pick up the item click on the potion in your belt.

Sixth: Now you have duped the item. One is in you inventory and one is in your hand.

Note: You have to be exact on the timing so this may take a while to complete, but if you do it constantly you will be good at it.