I’m sorry to admit I haven’t been in a position to attempt replicating the bug, but in the version that was on the Git as of about 16 hours ago,
I made a new character, found a flatbed, and tried to put my items away in the box in the cab.
The items appeared in the container, as well as duplicates -under- the vehicle, and it kept doing it repeatedly for every item I put in the box.
Edit: Huh. So this is entirely the wrong forum - my apologies