Redfoot sexing

Hey guys, I have three redfoots that were sold to me as Brazilian "cherry heads" several years ago. I bought them when they were much younger and kinda guessed at their sexes. I'm mostly a snake and lizard guy so I wanted to get an opinion on the sex of one of my tortoises from the tortoise experts.

The first one is my definite male and the second pic is my definite female. The third one I'm not 100% sure. I'm guessing it's a male but the under side is only slightly concave compared to my known male and his anal notch is not quite as wide.

Thanks for your help!

The top photo looks female (flatter plastron, short tail with cloaca at the base).
the middle and bottom two look like males to me (concave plastron, long, flatter tails with elongated cloaca in the center)

I have 2.2 redfoots. Both males have the elongated tails but only one has an extremely concave plastron... so much so it could serve as a cereal bowl; the other, not quite as concave.

Just FYI, the males may fight (and the competition may trigger more productive mating). The males may also try to bite the female so be prepared to separate them if this happens.

Thank you...I just realized that I posted the pics in the wrong order. The first one is my known female, the second one is my known male and the third one is the one I wasn't sure about but was leaning towards male. Thanks for your feedback! The male in the second photo is extremely concave but the other one is only slightly concave so I wasn't sure. I hadn't really paid much attention to the differences in their tail shape and length.
They've co-habitated for years and so far fighting hasn't been a problem. (knock on wood) They're in a large outdoor enclosure ( probably 15' x 15' so they have space to avoid eachother ). The female had one minor injury a couple years ago but it occurred while they were all feeding together and I think it was accidental.
I'll keep an eye on the two males to make sure they continue to get along.