I've had a long discussion with people on the differences between recognizing a face in a crowd (I know I've seen that person before) and identifying the person you see (That's the waitress from the diner).
Is there a short phrase for those faces (or other objects) that you recognize but do not identify? For example, when watching a TV show I frequently know I've seen an actor/actress before but not where and certainly with no knowledge of their name.
Unidentified covers those I do not recognize as well as those I do. Familiar faces works the other way in that it would also cover those I can name, but it is much closer to the sort of phrase I am looking for.