Item duplication and death screen (respawn problem)

Creeper blown me up and I could not click on the respawn button. It worked after few tries (10 or so, but return to title worked perfectly fine).
When I've been respawned my items were gone. So I tried to relog the world and while there where world loading animation I switched to another program. When I resumed the world items were back. Next I had to restart the world again because of villagers and iron golem were invisible (no sounds no hitboxes like they haven't been loaded). So now I was once more in the loading world animation screen and again switch the program while loading the world. When I resumed game my items were duplicated (they lied on the ground like I never picked them up).

(tried to replicate that but happened only few times while playing)
How to replicate

1. Get Killed by a Creeper
2. Respawn

If your items aren't there go to 3.
3. Go to title screen
4. Launch your world, while waiting switch to another program (ex. browser)
5. Resume game
6. Take your items
7. Go to title screen
8. Launch your world once again, while waiting switch to another program (ex. browser)
9. Resume game - your items should be duplicated

This should work. I also tried it on superflat but that doesn't worked for me.

And once I've done 5. my game kept on crashing.