Not exactly a “bug” but it’s something that is definitely not intended to be used like this. Thankfully I discovered it so it could possibly be fixed or monitored https://www.youtube.com/watch?v=fOGd8mq8_Y0&t=1s
Since this is considered and exploit, and since it’s not intended I’ve moved this to the Bug Reports forum. I don’t think that this works on PC, since the game autosaves as soon as you drop a weapon or move items in your inventory.
I should add that posting exploits goes against the forum Code of Conduct, but as it’s also a glitch I won’t be removing this post, hoping that it’ll be fixed in the foreseeable future.
Uh the bug exists like 4 years now or longer.
And it hasn’t been patched from console players.
It’s literally ruins the point for trading. You never know if you traded with an duplicated item or not.
Edit: and I can confirm it exists. I just ask an experienced Xbox players and he will say “yes” if the duplicating glitch still exists.