The parts for the helis might have come from an old factory that shut down, the parts might have been bought very cheap. Someone then decided to build some helis with the parts but clearly decided to forego the permit process and just forge all of the paperwork the customer gets. Someone buying them might have just been expecting a good deal on an older design but still legit helis or they knew they were not legit and were planning to resell them to other groups. I'm not sure anyone would actually want to fly in a heli they knew had forged paperwork.