Somehow a rogue in the Maze used switch places after taking lethal damage. That made the real me move where he was, as intended, but then left a immovable, untargetable, me where I was. The copy behaves correctly in regards to damage (see bottom) and our health/armor/auras are syncing (If I change equipment/get hurt/turn on/off sustains, his image changes as appropriate.)

I'm not stopped from doing anything. I moved on to the next floor glitch-free. I turned back to that floor to check, and yes, 'I' was still there.