While playing a multiplayer mission (not on a dedicated server), one of our players joined late. We realized that every item in the inventories of those already playing the mission were doubled. One FAK became two, four mags became eight. It even doubled the suppressors, which started in the inventory but we had equipped. We were using init line custom loadouts.

One player got disconnected and rejoined, and all our gear doubled again. The game deleted items arbitrarily to make room for the new items.