-This trick requires the W-Item materia. The materia is acquired after your party parachutes back into Midgar in Disc 2. After entering the subway tunnels in Sector 8, your party might walk away from the screen and encounter the Turks, or walk towards the screen to reach another subway section. Choose the second choice and follow the subway tunnel until it ends at a dead end with the W-Item materia.
-Equip the materia on the character with the item to be duplicated. When a battle begins, select the W-Item entry on the battle menu, select the item to be duplicated, then select any other item. Cancel that item, then select another item, then cancel it as well. Every time you cancel the second item, the one that was initially chosen will increase by one. Note: This will only duplicate item selectable in battle and can not be used to duplicate the various sources, materia, weapons, or armor. However, you have to already own two or more of a battle selectable item.
-Use the following trick to duplicate an item that you only have one of, and it can be a battle usable item. You must have the W-Item materia and have it equipped to any character. Get into a battle, then select the W-Item command and select any item you want to be duplicated which you have one in value of (for example, an Elixir). Then, select the character to use it on. You now have a second choice of an item to use. Instead of selecting the same item like in the original trick, select a different item (for example, a Remedy). After that, instead of selecting the character to use it on, back out once to the item selection screen. You will then notice you have one more of the Elixir (or the first item you selected) instead of the empty slot after you selected the item you only had one of. Select the remedy again and back out and you will have another of the Elixir (or the first item selected). Keep repeating this to get as many of any item as needed.