2 exposures in a single frame

2 exposures in a single frame. Two portraits of the same man, both wearing a white shirt with a pen in the pocket. On the left picture, he is slightly slanted. On the right photo, he faces the camera. No backdrop. Date of original material: [1953-54]. Size of original print/negative: 3 ½ x 2 ½ inches (2B). Format of original material: Glass plate black and white negative.