"Don't you know what duplicates are?" an incredulous Groucho Marx asks brother Chico in one of their better-known skits. "Sure," replies Chico, "that's a five kids up in Canada." The joke was a reference to the Dionne quintuplets born in Ontario in 1934, two of whom are still alive today. But of course we all know what duplicates are -- or do we? We're so used to the ability to make scans or photocopies today that the earlier copying technology of the 1960's and '70's -- the "Ditto," Mimeograph, or Gestetnermachines -- seems almost impossibly antique. And yet it's still possible to re-create some of these earlier methods of copying today, such as the Hektograph (above), a precursor to the rotary mimeograph which also used aniline dye; instead of mounting the master copy of a cylinder, it was simply placed in a bed of gelatine, and the dye allowed to soak in; subsequent copies were made by simply placing a blank piece of paper on the gelatine and then peeling it off. Simple Hektograph kits were sold as late as the 1950's and can still be had on eBay or Etsy -- or one can, fairly easily, make one's own almost from scratch. And, while you're waiting for the gelatine to solidify, why not read the Early Office Museum's excellent History of Copying Machines?