You searched for: “diplographs
diplograph (s) (noun), diplographs (pl)
Double writing, or writing two lines of text at the same time, as when producing embossed writing for the blind and ordinary writing at the same time: Sam was quite excited when he saw a diplograph in a museum, which  he found out was a Swiss writing-apparatus that looked quite clumsy.
This entry is located in the following units: diplo-, dipl- (page 2) grapho-, graph-, -graph, -graphy, -grapher, -graphia (page 24)