Does anyone here remember the twin-blade electric mowers? These were made by such makes as Sunbeam, MTD and Black & Decker, among others.
Unlike their single-bladed counterparts, twin-blade mowers run at higher speeds (read: two blades instead of one, obviously). I have a 1983 Sears Craftsman 91412 model (with the CPSC-compliant switch that you must hold down to turn motor on, let go and motor shuts off).
Sunbeam (later Aircap-Mastercut and MTD) and Black & Decker are two of the well-known manufacturers behind mowers like these.
Among the twin-blade mowers I'd like to find in the future:
Black & Decker U-273/8020 18" deluxe twin-blade mower
Black & Decker 8021 18" deluxe twin-blade mower
Black & Decker U-275(?)/8040 22" deluxe twin-blade mower
Black & Decker 8041 22" deluxe twin-blade mower
Here is a link that might be useful: Vintage 1956 Sunbeam Twin-Blade Rotary Mower