Why no Game A, B runs

I took a look at the differences between Game A and Game B, and from what I've seen it looks like there would be almost no difference between a speedrun on Game A and a speedrun on Game B. It looks like there would be no difference in terms of what would constitute an optimal time, and nowhere near large enough of an increase in difficulty to expect an optimal time to be significantly less common. For these reasons, I don't see the need to add a separate category for Game B.