She appears to be the same model as Sophia with a few modifications, what she has in common with Sophia is the size of her nails (not the color), the size of her butt, and the type of hair.
His back doesn't look as exercised as Sophia's.
Plot twist: It's really Sophia (wearing a wig and painted her nails a different color), she made a deal with Logan, if he had sex with her and he left Ellie alone she would have sex with him, so Sophia and Logan got together. They agreed to have sex so Ellie finds them red-handed. (Logan invites Ellie to her sorority as planned with Sophia)
Or else Logan is actually having sex with another woman for Ellie to find and put pressure on Ellie to have sex.