As soon as you do start comparing this odd couple, you discover there is more to this birthday coincidence [of being born on the same day in 1809] than the same astrological chart (as Aquarians, they should both be stubborn, visionary, tolerant, free-spirited, rebellious, genial but remote and detached—hmmm, so far so good). As we approach their shared bicentennial, there is already one book that gives them double billing, historian David R. Contosta’s “Rebel Giants,” with another coming early next year from New Yorker writer Adam Gopnik.