The game makes sure that the player entity is never destroyed, but in
doing so, it doesn't destroy any duplicate player entities that might
have been created via strange means e.g. a custom level doing a
createentity with t=0.
Duplicate player entities are, in a sense, not the "real" player entity.
For one, they can take damage and die, but when they do they'll still be
stuck inside the hazard, which can result in a softlock. For another,
their position isn't updated when going between rooms. It's better to
just destroy them when we can.
