Hi guys, I posted a duplication glitch here a few months back but this method is far superior in comparison. Had a lot of people asking about this method recently in my Discord so thought I'd do a fresh video on it. Hope this helps out, thanks for watching
Step 1: Join a friend and then go to your vault.
Step 2: Double tap or spam A/X on the weapon you want to deposit, check your vault and it should be duplicated.
Works without a hitch on far connections/slow connections, but having the host spam LB+RB or L1+R1 in their vault will get this working if you live close by or have a strong connection. Enjoy!