Item Duplication -- Glitch Explanation/Tutorial [Fallout: New Vegas/Fallout 3]
You can duplicate an item spawned in a container (spawned dead bodies also work) by depositing a stack of 6 or more other items with weight, then withdrawing them by pressing LMB and A almost at the same time.
The reason the item needs to have weight is because of the confirmation screen you need when withdrawing. If the item has no weight (such as ammo or meds) you will not get a confirmation screen.
The reason you can't dupe items from your inventory is because those items have a Reference ID, whilst items spawned in containers does not. Read more about item ID's here: http://fallout.wikia.com/wiki/Form_ID
This glitch works exactly the same in Fallout 3 as it does in New Vegas, and should also work on consoles (Only tried it with a controller)
Other Videos By Kungkobra
Other Statistics
Fallout: New Vegas Statistics For Kungkobra
Kungkobra currently has 1,187,750 views spread across 110 videos for Fallout: New Vegas. His channel published over 3 days worth of content for the game, or 84.54% of the total watchable video for Fallout: New Vegas on Kungkobra's YouTube channel.