The cool bit about being an eccentric millionaire superhero, is that with all that money you get to create any product with your name, even Matryoshka dolls.
Batman and Iron Man, or Bruce Wayne and Tony Stark, have that much in common. We can totally imagine the both of them chilling and wondering what to do with all their money, after a long session of crime fighting and/or saving the world/galaxy, and saying “you know what we should do? Matryoshka dolls, dude”. Yeah, we bet that’s exactly how it happened. Except that the evidence points at the Herochan guys as the original source of these pictures.