You will need:
2) Things that you want dupe
4) The bandage on hand.
1) Wear the backpack.
2) Putting things in a backpack that you want dupe.
3) Once all the items are collected - stand for 1 minute and do nothing.
4) A minute later drop the backpack with the things on the ground and crash the server.
5) Go back to the server and take a backpack from the ground.
6) Congratulations! You have doubled your things!
Just as a guide Dupa-equipment, but for this we need an additional tent / barrel / machine:
1) Take the gun in the hands.
2) Stand for 1 minute.
3) Remove the gun in the tent / barrel / car.
4) Crash the server.
5) Go back to the server.
6) One weapon will be in your hands, and the other where there you have it drop congratulate you again duped things!