It was a little bit difficult to reproduce the error because the server restartet randomly (sometimes after a half hour, sometimes one hour, even sometimes after 20 minutes). But if you want to reproduce it, just change a inventory object with a similar one on the ground shortly befor restart (i would say about 30 to 20 seconds before restart).

This is maybe seem not such a big issue, but when you run your own server it's easy to double weapons and other stuff because you can restart the server on your own (it's not allowed, i know, but people do it anyway). I was able to double even a loaded rifle. I just changed it with the same type of gun, which was not loaded. After restart, the gun in my inventory and the gun on the ground were fully loaded. I think it would be possible to even double the whole backpack, because it worked with a jacket and a apple (the apple was placed in the jacket). After restart there was the same jacket on the ground and i had a second apple. I just did this for research (i was standing in the woods for about 20 minutes always changing the jacket), i didn't use any of the items i doubled that way. I just wanted to know if my intuition was right. Also, sorry, i forgot to make a screenshot.