My brother and I are the same age.*
We're reading a book, and on the same page.
We like the same sports and dress just alike,
but have to take turns when riding our bike.
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Time has expired on this question and it's time to give the solution: The two brothers are part of a set of TRIPLETS. The third triplet is a girl.
You stumped me! And yet, your answer was so simple. You are amazing!