ive just seen a lot of optis before. Im not a hundred percent sure, but that looks like its a very old wooden opti. Optis were designed in the 50's as a boat that could be made from 3 sheets of plywood, the model just evolved from there.
All Optimist dinghies are knock offs in a way. They are made by many builders all over the world to a set of plans. If your boat measures to the plans then it is an Optimist Dinghy if not it is not a legal boat to race in that class. As you say it could copy but not a registered class boat. Ontario yachts may have built a class Optimist but I can’t find any record of that. Ontario yachts builds Etchells class boats to this day call Dirk at Ontario yachts he may know the history of your boat