Then of course there's hyper dispensationalism with it's invention of a class system. The lesser being those in the kingdom of God (a made up earthly kingdom of slaves), and the kingdom of heaven (for the elite heavenly country club people).
Don't forget STP's third group of people. They inherit a city. They are different than the earthly kingdom slaves and the heavenly country club people that he claims will exist at the same time as his city people.
Check out his signature for more details.
That's the problem with Dispensationalism. They have to keep making up stuff and adding stuff to it every time they find something wrong with Darby's original theories.