If you look hard at the photo of my Saxon on woolly, the snap with an enlarged section of the r/h side crank on, you can see that there is a
seam between the top, cotter pin section and the octagonal one. There is a minute gap between the octagonal section and the lower, pedal thread one, too, which is not visible on any of the photos, sorry.
Also, fwiw, a friend of mine who used to ride Duprats in the fifties says that they were rather fragile.
Hope that helps.
Regards, Toni Theilmeier, Belm, Germany.
P.S.: Sorry not to have cc´ed this mail to the lister who asked the question, I have already deleted the CR digest.