Duplication

 (also known as duping) is a process by which the player creates multiple copies of an item using an exploit or glitch.

Multiplayer

 * 1) Ensure autosave is off.
 * 2) Visit a friend and drop off any stuff you want duplicated.
 * 3) Exit without saving, then have them invite you back. You will rejoin with all of your original items, and the items you dropped will still be there, waiting to be picked up.

Ice Rod

 * 1) Place a storage object that can hold items.
 * 2) Fill the container with any item(s).
 * 3) Use the Ice Rod on a corner of the storage.
 * 4) Use a hammer to break the container.
 * 5) Enjoy infinite storage.

Mechanisms

 * 1) Place any chest on top of at least one Active Stone Block.
 * 2) Place any item(s) in the chest.
 * 3) Use Wire to connect the active stone to a Timer.
 * 4) Activate the timer.
 * the chest duplication bug was fixed in 1.2, but there is another way that wasn't fixed(the 2nd photo)CHEST_DUPE_NOT_FIXED_LOLOLOLOLOL.png

Pumps Method
Using pumps, you can make a duplicator which will automatically make more Water or Lava. To do this, you will need an Inlet Pump, an Outlet Pump, water/lava, Wire and a Timer. Connect the Wire to the Timer and both pumps. Activate the timer and wait.

Refilling the Ocean (Video)
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"Doubler" Duplication

 * 1) Go to the "Players" folder in your Terraria folder, which can usually be found at C:\Users\USER\Documents\My Games\Terraria (or just use the search function in your start menu).
 * 2) Start a single player game.
 * 3) Put any item you want to duplicate in your inventory (very important) and save and exit your game.
 * 4) Look in your "players" folder: there will be a file (or multiple files if you have multiple characters) which looks something like "Player1.plr".
 * 5) Copy and paste this file so that there are now two of the same file in your "Players" folder (the name will change to "Player1-copy.plr" or something close to this).
 * 6) From Terraria's main menu, reload your game. You will notice at the character selection screen that you now have two of the same character to choose from. Choose the second one and continue to your world.
 * 7) Once in your world, take the item you wish to duplicate and stick it in a chest (it helps to place a chest right next to your bed or spawn point in order to save a little time). Save and exit.
 * 8) From Terraria's main menu, reload your game with your original character. Now your original has the item you wish to duplicate still in its inventory, as well as in the chest.
 * 9) DELETE both the original AND the copied file in your "players" folder BEFORE you save and exit your world. When you save and exit, a brand new save file will appear in your "players" players folder.
 * 10) Save and exit your world, copy and paste your most recent save, rinse, repeat.

Not working in 1.2: You need: 1 NPC (not guide) The item(s) you want to dupe Money! First open the shop from a NPC, then select the item you want to dupe, sell the item buy it back, now you can buy it again, and again. This can be done with every item, so long you have money enough.

With Chests

 * 1) Place the item you want to duplicate in a chest then exit the world.
 * 2) Select multiplayer, then the "host and play" option.
 * 3) Select the world where you have the item you want to duplicate.
 * 4) Retrieve the item from the chest.
 * 5) Exit the world, then enter it on single player mode.
 * 6) Retrieve the item from the chest again, then you should have two of that item.
 * 7) Note, this may not work sometimes.

Without Chests
Requires two system accounts; works with one controller, better with two.

''There are two points in this process at which the game must be saved. If the game saves anywhere else you must start all over from the first step.''


 * 1) Load both system accounts and have them stand about 3 or 4 body widths apart facing each other. Have the second accounts inventory open so you can tell when they have picked up everything - also have them give you anything you intend to copy. Now save the game. Timing is important over the next few steps; there are several points at which the system will autosave your data.
 * 2) Give the stuff you want copied to the second account on your system (open your inventory and drop the items so the other account can pick them up).
 * 3) Have the second system account exit the game through the start menu as soon as you are done gifting them your items. This saves their data so don't skip this step.
 * 4) Force quit as soon as the other account is out of the game. This prevents the game from auto saving your empty inventory after they exit.
 * 5) Load both accounts and retrieve your copied items. You should have doubled your inventory goods.

Bugs

 * This may cause the world you used to not load the next time you start the game, which causes the system to lock up. Loading a different world, returning to the main menu, then attempting to load the map that wouldn't load should resolve this problem.

Console Videos
thumb|left|330px|This is how to Dupe in Xbox 360 (Multiplayer)

thumb|center|330px|Duplication on Terraria: Console (Single Player)