[quote=@Prince of Seraphs]

Just because the faunus might have animal ears doesn't mean they don't have human ears. It's actually a very common precedent in genetics, organisms evolve with a new organ or something to do a better job than the old one but the old one takes another three thousand years to be edited out of the gene pools. Maybe faunus in three thousand years will have cat ears but no human but they're not like that now.

Plus you'd just look really creepy without ears.
[/quote]

I'm fairly certain, I heard something concerning the still remaining human ears from one of the crew saying that they were unable to remove them from the skeletons or something, since all their concept art shows Blake and Velvet without human ears. Later they just changed it, so that they do have human ears.

However, biologically it doesn't make sense for a mammal to have two sets of ears and I'm sure Faunus are still mammals.
Or at least, not both of the pairs actually work at the same time.