Can you tell who is who?

Can you believe how much they look alike? When Zac was first born I didn't think they looked anything alike but now they're really starting to favor. The pictures in order are Zac, Mack, Zac, Mack. Now keep in mind Mack is a little older in his pictures but close enough. Anyway thought it would be fun to compair some adorable pictures of my little men!