The answer is 12(United_States.) I was guessing 3, for sure: Man-O-War, Citation and Secretariat. Usually it’s some decades inbetween wins, but we had 3 in the 70’s alone! Secretariat (1973), Seattle Slew (1977), Affirmed (1978.) I don’t remember the last two because ♪ “Then I got high, then I got high, then I got high.” ♫
Too bad Seabiscuit couldn’t run. He could have won, but he was the wrong age or something. War Admiral, his arch enemy won in 1937 and Seabiscuit soundly beat him a year later: ”…two hundred yards from the wire, Seabiscuit pulled away again and continued to extend his lead over the closing stretch, finally winning by four lengths despite War Admiral’s running his best time for the distance.”