Duping Items that actually works!!
Someone bumped a thread from back in August for a method that has been patched so I thought id put up a way that hasnt! (Need 2 People)
1- Put whatever you wanted duped into a backpack
2- Both players drop their backpack and look at backpack that needs to be duped
3- Both players scroll down to 'Take Backpack'
4- Count down and both pick backpack up at same time!
You will both be wearing a backpack with same contents. Players need to log out and log back in for it to be set in stone as if a players moves and items out it will move in both backpacks...
1- Put whatever you wanted duped into a backpack
2- Both players drop their backpack and look at backpack that needs to be duped
3- Both players scroll down to 'Take Backpack'
4- Count down and both pick backpack up at same time!
You will both be wearing a backpack with same contents. Players need to log out and log back in for it to be set in stone as if a players moves and items out it will move in both backpacks...
...Nice find. If I ever go back to playing legit, I'll try this out. But then again, that's not playing legit 

at the end
but it's always faster to just spawn in a box with 100x of each weapon