To dupe in multiplayer, its really easy, (take advantage of this fast, you can dupe guns and ammo and food and everything!!!)
To do this, simply you need to lag your connection, (not enough to make you time out)
To do this either get a way for you to start lagging (There are programs to make you lag) (make sure your in a safe area away from zombies)
Or if your on a server with a bad connection already, this should work. Ok,
1. When your lagging, drop the item you want to dupe
2. Spam E on the item you want to dupe (Sometimes it takes a little bit to do it. you need to start lagging)
3. Check your inventory, and the item should be duped
-Thanks me for this please!
Other Method - By Zarix
go to your games folder data then config and edit your recipes with notepad like metaltrussing needs alot of stuff, you change the recipe to like <recipe name="metalTrussing" count="900">
<ingredient name="stick" count="1" grid="-1, -1" />
<ingredient name="stick" count="1" grid="0, -1" />
<ingredient name="stick" count="1" grid="1, -1" />