I have a question. Breeding a Super Giant female with a normal male is safe or potentially dangerous? Is it acceptable breeding practice or should be avoided at all costs?
You'll want to observe the mating process, and make sure that if she says no, the male backs off. There's usually no fighting or injuries as long as they are both on the same page.
As for housing 2 females of different size, it's never recommended to house geckos of different size together. While I think super giants are usually more docile in my experience, there's no guarantee they'll get along, and no guarantee the larger won't bully, or the smaller won't feel intimidated. Often it's actually the smaller one that ends up being mean because they're intimidated. Kind of like a short man syndrome.