TOKYO—Ariarne Titmus has defeated Katie Ledecky again at the Tokyo Aquatics Centre. In fact, Ledecky didn’t even win a medal—the first time that’s ever happened to her at the Olympics. The Terminator gave the Australian women their third individual swimming gold of these games with a victory in the 200-meter freestyle. Titmus set an Olympic record of 1 minute, 53.50 seconds to make it 2-for-2 against the American star, following up a thrilling victory in the 400 free. In the longer race, Titmus conserved her energy over the first half of the race, then rallied to pass Ledecky with the second-fastest performance in history. Ledecky wasn’t even close in the 200, making the first flip in seventh place and never getting higher than her fifth-place showing at the end. The defending Olympic champion finished in 1:55.21—nearly 2 seconds behind the winner. Ledecky faced a grueling morning that also included the …