Singer Twin fans...
Pete,
The Singer Twin fan design goes way back to 1949 with the first dual suction "magic carpet" upright. These were Singer made, and were around in this 1949 design with a few changes until about 1963-64 when Singer changed the looks and came out with their U series upright. These were heavy, hearty machines, they cleaned well too. Problem was the motors were not very good, and the ductwork was small, the clogged very easy! The U series was around until the early 1980's, about which time the Singer sewing stores started to disappear...
The twin fans came back in the middle-late 1980's made by Ryobi. They were now mass marketed at places like Wal-Mart and such, but still the sme basic design as the U series, except now mostly all plastic.
In their heyday in the 1960's, Singer made those twin fan uprights for LOTS of people, among them: Kenmore, Sunbeam, Westinghouse, and in Canada for Lewyt.