I'm running experimental and my friend is running stable if it is of any consequence.

Yesterday me and a friend were looting up and swapping items. In particular magazines for guns.
the first time the issue happened it was when I was giving my friend three (full) glock mags. He took the three mags I put on the ground but there was a glitch where even though he had taken all the mags (and could see no more on his UI/screen) I could still see one on the ground. I could then click/drag this mag from the ground (although the magazine was actually in my friends inventory) and put it into my inventory effectively 'stealing' the magazine back directly from his inventory.
This 'ghost' magazine seemed to persist on the ground and I could take the mag back regardless of how far away my friend moved from it.
Also, even when the magazine returns back to my inventory there is still the 'ghost' magazine on the ground.
Also, at no time can my friend see this 'ghost' magazine except for when I actually place the mag back on the ground so it seems to only show for the person that puts the magazine down initially.

It also later did it with a bunch of 5.45 30rnd AK magazines I put on the ground for him/

It doesn't seem to happen when my friend places items on the ground however, so perhaps this is an issue that is caused by the exp client?
Although we haven't tested it to any serious lengths.