All you need is a Zorki 1, a Leica III and ONE roll of film.
Actually, it was one quite accidently I'm afraid. I couldn't do it again in 50 rolls worth of trying. I took a few shots with a Zorki 1 back at the end of summer, then decided to tinker on it a bit, pulled the roll out, marked it "5 shots" and threw it in the bottom of the bag... and forgot about it. So today I spotted it, and just wanted a few more shots before going home and "re-loaded" it into the Leica III and fast-forwarded to frame 10. Surprise! I had originally taken more than 5 shots and 3 came out double exposed. ......... See? It's easy.
I'm sure my wife will use the shot as evidence.