Steak said: How come one twin is so much more popular than the other?
Its mosly because, in game, her personality comes off as being the 'Aloof/Tsundere' type. Who likes to gamble, express herself openly and be a free spirit. Whereas her sister is the 'Determined/Reserved' type. Who is more of a 'big sister' to her twin, but doesn't speak her mind as much and is more introvert.
It also helps that she's a dancer who wears provocative clothing. Further extending her personality traits.