Firing offset would probably not gain you anything, most Engines that use a Dual ignition use them either for better Emissions and a Cleaner Burn, or for more Power in the same way, this works because of the Big combustion Chambers, in wich you sometimes can't burn everything inside, that won't really work on our Engines witch most of the time have combustion chambers that are Hemispherical and really small.
Or they use them for reliability, for instance the Old Porsche 24h Racing engines had them and Planes use them so that if one System dies the Engine still works mostly fine. this would probably be the only reason to use them on a Moped, except for maybe coolness factor. (edited)