@Zeb
Not exactly, they are not separate like Daybreaker or Nightmare Moon. More like King Thorax, so all Sci-twi images still have Twilight Sparkle tags, so it would just mean yet another tag that means the same thing is added on. You can get the exact same results from “Busty Twilight Sparkle, Sci-Twi” without the need for “Busty Sci-Twi”.