If you edit a crate like "Box_NATO_Equip_F", then customize the equipment storage (Vanilla things), you can easily overload the crate capacity.
The issue is, in that case, when you pick a uniform or vest or backpack (say any container, not an item):
- your previous uniform or vest or backpack goes on ground ("groudWeaponHolder"). Normal, there is not enough room in this overloaded crate;
- you catch your new stuff. Normal, the exchange works;
- BUT, your new stuff is not removed from the crate, so it is duplicated. If you drop your new stuff on ground, pick you old stuff and renew the exchange, you can re-drop your old stuff, gain a new stuff not removed from crate and add it on ground, ETC.
NOTE: this duplication doesn't occur on crates with enough room or if your inventory slot is free for picked stuff (no exchange, just a grab)