Yay! I am waiting on my youngsters with the same issues, both hatched together, but developed differently, but I swear they're both girls?? I figure I have to wait til they either lay an egg, or crow! They look the same as yours though. And my Adult Australorp hen has huge comb and wattles, so I wasnt surprised to see that in the one like yours/mine, but just leary that it mmmaaayyy be a rooster too? Thanks for the update.
I would not give up until you hear them crow. Two out of three I posted pictures for that people though were roos turned out to be hens. It was fun though guessing.