I don't think they're going to be twins. In fact, I think one is a girl, and one is a guy. Seems as though one of the lead roles in FFXIII Versus is a guy... and FFXIII is a girl. You know how SE roles, they always make their characters look feminine, even if the character is a guy. Just look at the exotic hand-drawn images of previous characters. They all have feminine characteristics, so maybe one of those are a guy and one of those are a girl, in the logos.