Then, kill yourself by using Deo-Bombs or Molotov's.
When you reach a checkpoint during any campaign quest in Solo mode, drop the item(s) on the ground you want to duplicate (you can drop all the items in your inventory). Exit out of the menu, and pick up both items. Then, choose to drop the weapon that is equipped. Select 'Next Play' to start a second playthrough with all previously earned money and inventory items (blueprints, weapons, etc.).
