In 1999, on a kayaking trip in Canada, my partner Jane and I visited an island that had once been a native habitation. There, a member of a local tribe, Tom, presented a lecture on the history of Canadian First Nations. At about the same instant, two photos were taken of Tom on identical Kodak disposable film cameras -- simple box cameras that have no user-adjustable settings and are incapable of double-exposures. The first photo below was taken by me and the other one by a member of our group, Becky, who had been associated with the Lily Dale spiritualist community.
Becky's image was scanned from her original negative strip, which she sent to me.
Kneejerk skeptics might say, "Oh, she must have rotated the camera while the shutter was open." But that would have been physically impossible for a number of reasons and in any case would have produced radically different effects from the ones we see here.
Study Becky's photo carefully and note how the very dark center of the far timber frame has been replaced by what looks like dense foliage. Also note the small, puffy "clouds" in the foreground.