This isn't like an expert opinion, it's just based on how I RP.
Yeah, my Kelvic coyote recognizes different races and especially cultures as having different scents. It sort of makes sense because each race typically has its own things it does and eats and focuses on, and I imagine a person's scent to be made up of all the scents around them along with their own particular smell. Even without having different cultures to influence scent, I think different races might smell differently based on simple body chemistry. Does an Akalak's blue skin, large size, and typically huge musculature have different chemistry than a Zith's body or Human's? Obviously Nuit would be easily recognizable unless they consciously used something to try to mask their scent, considering that they aren't living at all.
As for recognizing other Kelvics, I know the wiki says they don't intuitively know, so they don't see each other and think 'oh that's a Kelvic', but because of the way I RP and the way I think I always assumed that they would smell like the animal they are. So a Kelvic horse might still have a lingering scent of horse, especially if he had just shifted. Being as Kelvics aren't exactly animals but they aren't exactly human either, it might make sense that they too, have a unique sort of body chemistry that contributes to their scent. But that's just me conjecturing.
Hopefully my interpretation is okay, though, because I've had Kyo identify other Kelvics based on scent. It's always mildly puzzling to him because predator-prey dynamics usually come into it, so if he meets a bird Kelvic he might consider eating her (but only if she's not in human form). ^_^' Oddly enough though I don't go the other way; he's never identified an animal as a Kelvic, but then again I'm not certain he's ever met a Kelvic in animal form without already knowing them. So I guess I just assume the 'animal scent' overrides the human. That, or because Kyo likes humans a lot more than he cares about animals, he might not think too deeply about an animal's scent other than to loosely identify-- like 'fox' or 'mink' or 'chicken'.
Logically though, Kelvics would probably smell like a mix of both? Unless for some reason they were always in animal form or in human form.
Anyways, I guess I sort of think as scenting as an olfactory sort of aura-sensing; depending on the nose maybe it can tell you vaguely where a person's been or who've they been near or what they ate earlier, though obviously it's probably not nearly as in-depth as actual auristics.
Scenting is just a perk of being Kelvic, if, that is, your animal form is one that actually has a better nose than the typical human's.
EDIT: Like you said, the only way I can think of that would make sense for Kelvics not smelling like their human/animal form would be if the shifting magic somehow 'erases' their last scent. Like it gets zapped away. I suppose it's possible, but I never really considered it before!