The old Tower Snappy was a very primitive camera compared to the inexpensive models of today. The aperture was preset and the shutter had only one speed. The film was wrapped in paper with a black lining to block light. The outside of the paper was of a different color with the frame numbers printed on it. The film was advanced manually buy turning a knob while watching for the next frame number through a small red window in the back of the camera body. There were no safeguards to protect from double exposure so if one forgot to advance the film between shots a surprise awaited them when the photos returned from processing.
The above photograph of my Dad with his first school bus is an example of the accidental double exposure. Although the image is jumbled it has remained in my collection of snapshots from my early years