Step 1: What You Need
Land, Minecraft PE, the item you want to duplicate, a chest, and YOU.
Step 2: Chest
Put your item in your chest.
Step 3: Quit To Title
Quit to title. Go back on your world.
Step 4: Take A Walk
Go 50- 100 blocks away from your chest.
Step 5: Home
Go to your home screen. Double tap and hold down the app Minecraft. Tap the minus button. For iOS 7, double tap and slide Minecraft up.
Step 6: Almost Done...
Go back on to Minecraft and your world. Then walk back to your chest, open it up and your done!