A pair of Brown University-bound Long Island twins did what no other siblings ever have in the history of prestigious Chaminade High School — finish their academic tenure as both valedictorian and salutatorian. Recent grad John Gomes, 18, earned a cumulative 99.42 over four years and edged out his younger-by-a-minute brother Joseph Gomes who put together a hard-fought 99.29. “There have been a couple of times where we used to boast about who does better in calculus, who does better in physics,”