well, there are single blade electrics if you look past just the Greenworks brand. (and even they offer a smaller single blade cordless IIRC)I am really loving the new Greenworks 20" twin blade mower. I would definitely want to use it in my lawn. But I am a little bit confused to see a twin blade in a 20" mower.
This is not like those old Sears/w'ever twin blade corded electrics - the bushings would wear out in 2 seasons on those.
This has 2 motors, offset and slightly overlapping. It is load-sensing too so, it boosts power when in thicker/taller grass.
Investigate the Lowes Kobalt line. That may be what I'd get now.
keep in mind though - deck width is NOT the same as cutting path - electrics seem to ALL mislead on that.