I was building a tower of dirt to mark my house and I fell off. I picked up all the items and then dug up some dirt, and closed the screen. The system restarted the game. My inventory was as I left, but my stuff are all over the floor again so my items got duplicated. (My shovel was on old durability). On another world I lost several minutes of progress after my system killed the game when I was afk.

I think the same bug was present almost two years ago, before infinite worlds came out. My friend was able to duplicate a whole inventory of diamonds by jumping off high pillars, pick up everything, walking 50 blocks away, killing the process, and picking up the diamonds on the floor (for the second time).