The "persona" thing for these 3 can be bit confusing.
"Thief King Bakura is used as a pawn by Yami Bakura. He is a similar, but distinct entity from Yami Bakura. The Thief King was the ancient half of Ryou Bakura." - YuGiOh wikia
I'm going to leave the "multiple personas" tag. I say this because there is also a "dual persona" tag on Danbooru, but like I said...this situation is confusing.
