Does it make it weird that if they "De-evolve" into their Rookie forms they're both cats? That would be an awkward moment after doing the deed.
It depends on where your stance is on furries, but also they don't necessarily evolve from Gatomon/BlackGatomon. Darcmon is also a champion Digimon that evolved into Angewomon, as is Angemon, and LadyDevimon can evolve from Devimon or even Devidramon. Not to mention that LadyDevimon originally dark evolved from Angewomon in the lore, just like Devimon did from Angemon. (Digimon can evolve into same stage forms. In fact, Megas do it all the time when they mode change or DNA Evolve and Devimon was a Dark Evolved Angemon in the original Digimon World game for PS1, which came out before the anime.) So it depends on whether or not they even evolved from cats.