I had an empty medikit in my inventory that I was saving for later. I found another medikit on the ground. This one was full.

I dropped my empty medikit on the ground. They probably "stacked" so it disappeared from the viscinity window.

I took the full one and put it in my inventory.

Surprise, the empty medikit I previously dropped is now full. (not exactly the same amount of stacks for the pills but same content).

I'm just thinking about this now so I didn't think about reproducing it but I will.