First you need to find two stacks of hay. Drag them into your inventory, next click on one of them and then drag the other one onto it and eureka! You have your very own portable bed (just click on it to use it) it may take up a lot of space but it is very useful for big battles.
Open you inventory left click the item you want to duplicate. Drag it outside of the inventory screen and (Make sure there is an X on the item) While still holding the left mouse button press Cntrl + L
(Quick load) while the game is quick loading and the load bar starts to fill let go of the mouse button when the game loads your original item will be in your inventory and the duplicate will be on the ground where you put it.
Quick save before you try this and when it is successful quick save again before you try to duplicate another item or they will be lost.
If you have 20 super potions it will duplicate 20 super potions giving you 40 total it works with everything as far as I can tell even money. I noticed with weapons though that when the one your are using receives damage the duplicate does too.
I found this on accident and it took me awhile to realize what I did and a little while longer to figure it all out.
There is a glitch that allows you to put as many charms as you want in a charmable weapon. At the weapon's display, click on the weapon to show its charm slot, then continue clicking on it to continue pulling up charm slots. When you have as many slots as you want, put your charms in them. NOTE: You can only do this trick once. Remember, it is a glitch.
This is much more simple than any other multiplication cheat..
All you need to do is open a trade box with any character, then go to give them any item that you have more than one of, eg: Gold.
When the box asking how much you want to give them pops up, enter a negitive amount.
The items then get multiplied, eg: if you had 20,000g, there will be around 30,000g or more in BOTH your invent. box AND in the sending box.
Remove the gold, or send it to them free of charge to improve their respect for you. (All the people I have met now have 100 admiration points for me )
This works with EVERY item i have tried!
Dont worry if the amount of items diminish, just keep doing the cheat and after a little while LOADS of the items appear!!