You need two main weapon and two player.
1. Take weapon 1 (in your back)
2. Press "F" for take weapon 2 in your hand
3. Disconnect and the weapon falls to the ground
4. player 2 just take the weapon 2.
5. player 1 reconnect, and he have always the weapon 1 & 2.
The weapon 2 has been duplicated and any equipment attached.
ENJOY :)