Two centuries after their famous forebears met on the banks of the Hudson, the Hamiltons and the Burrs are still at it."LOOK AT THIS," said Antonio Burr. "Look at what they're selling." Standing in the gift shop of the New-York Historical Society on Manhattan's Upper West Side, Burr held a magnet to the light. On it were portraits of his ancestor Aaron Burr, the third vice president of the United States, and Alexander Hamilton, the first secretary of the treasury, whom Vice President Burr killed in a duel 200 years ago. Each man's portrait stared coldly at the other's.It was...