Spawned in survival mode with cheats enabled on new world. Entered creative mode and created nether portal. Entered nether and destroyed portal. Switched to survival mode. Played normally for an hour or so. Eventually died. Respawned in the overworld, unable to interact with nether portal. Relogged into the world. I was now standing inside a second copy of myself with a visible username and STILL unable to interact with the world, or even move.