After reading Japan Wikipedia, it was revealed that both Ultraman Geist (Actual name Ultraman Dark) and Ultraseven Geist (Actual name Ultraseven Dark) are actually the Dark Lived Ultraman and Ultraseven. Unlike Tiga Dark, they have their own Dark Live host.
The Tsubaraya Prod. use the suits of Ultraman and Ultraseven Geist as a remake. Also, there is some data I've read that Ultraman and Ultraseven Geist are modified clones of Belial.