Pam’s answer to “Can someone confirm that part 3 is supposedly from Iris because Ben mistakes Summer and Iris on the…” > Likes and Comments

I guess that's why the author had him tap on her window and the end of Part 2 and confess he couldn't actually tell them apart. He just knew it was Iris at the hospital because of the way she was smelling the flowers. The Iris sections also tried to bash us over the head with the "you can't really tell twins apart, you just have to go off the way they behave." I've encountered plenty of twins in my life and never had an issue so it all felt like a stretch to me.