It has been fairly common for canoes to be fitted with sailing rigs after-market. Was yours shipped to a dealer? The dealerships carried sail rigging and could have added it at the time of sale, or at any point. The most common canoe to be fitted for sailing at the factory was the HW model, but any canoe model could be used (the HW was considered the best suited for "heavy water"). It's also common to see a mast seat, such as yours, with a step below it, that never had any other sail rigging and was never actually used for sailing. If you post the serial number of your canoe, I can look it up-- or check yourself and see if the build record says "mast seat and step", in which case that was added at the factory.
As far as I know, Old Town seats had the 7-step design when shipped from the factory. The 7-step design is the one you see on dining room chairs and the one in the sheet-cane pattern. Your seat appears to have what's sometimes called "canoe weave", and it was probably re-done by someone who knew this particular pattern. I know PennYan and Detroit Boat Works canoes were shipped from the factory with this design and probably some others as well-- it seems to be a little "springier" and is pretty.
If you want to attach more pictures, one of the deck would be nice. Deck in the picture doesn't look like a mid-30s Old Town deck to me. You could have something else, and that might explain why there's no mention of the mast seat on the build record.
Kathy