Okay, let's backtrack a little bit.
Early in the morning, Darren came down to have a breakfast and it ended to be the twin's curses and tattoos. He managed not to gape but his mind surely is. Why?
This is how he calculates it. The Elroy twins is composed of one being a famous lawyer and the other a runaway prince, it's completely different and apart from each other.
But they are way too good looking for Darren's ability to keep himself from swooning, staring, and behaving. True, they may have different personalities because one of them is a fake and the other genuine.
But they are both attractive. They have this ability to be their own person despite the similarities they may have physically but then again, they are literally the same from the outside, an exact carbon copy and replica.