Omg thats an actual explanation of that. I was told by an "expert" that they werent normal beastmen, idont remember very well if they were too human they still have features of them or smt else like mutation. They have a name tho, i even read a manga of it but it was too long ago. Some authors do it by aesthetics but mangakas are the ones who explained the reason of 4 ears, it does have a story!

A pet peeve I have that I can't seem to stop seeing is when artists draw human-animal hybrids with both a set of human ears AND animal ears. Like ????? Tf they need four pairs of ears for??? That's gotta be hell. Just a nitpick of mine because it usually means they havent cared to look at the details