This trick works on any item you can use in battle, such as Elixirs or Phoenix Downs. Enter the item menu outside of battle. Move the item to be duplicated to the first slot. While in battle, choose the item menu, then press Up + A. If done correctly, you should see a flash of the equipment screen before seeing the main menu again. Press B to cancel. The item is now duplicated. You can repeat this as many times as desired, but be careful not to get more than 99 of an item as it may glitch your game or saved game file. Note: Items can be in either the top left or top right hand corner to be duplicated.
