You're ignoring all of the other racers. Day 6 had Aster, Priscilla Gladiolus, Southern Cross and Yulan.

Yeah. You're right. That a curious coincidence. Maybe was just lucky.
But it change nothing actually. If I'm right, the results are true and it's easy to get all the bets. If they have just randomized the race, nobody can guess the Nutaku winner and win all the races. In any case, I guess trying with DMM winners is the best thing to do now. If I fail and Yulan don't wins... I hope someone has a better idea. If Yulan wins the race, let's try Justicia.
At least, it make this event a bit more fun.

So, sorry if I'm wrong. I used that result list without referring to the wikia page.