This is a photo I discovered recently on a film that had been sitting in my analog camera for ages. I neglected the camera badly after I got my digital SLR. I vaguely remember where I took it, but I have no clue how the double exposure happened. Normally the camera blocks the shutter until the film has been forwarded.
However, I don’t really care how it happened. I think it’s an excellent accident.
(Sorry for the bad scan, my technical skills aren’t the best. )