The items are duping and taking space for nothing, all the items you can attach on a weapon / clothes are duping.
I'm trying to put my PSO-1 on my AKM but it won't, and it dupe the PSO when I move it, the only way to fix it is to put your weapon on the ground.

It's doing that bug for all items like PSO, Scope, Batteries, Gun in a holster, etc.