i've had that happen, and for some reason, my own looks trigger this response in others *a lot.* anyway, i've thought about it for awhile (like a couple years, lol) and finally, my conclusion was that basically, there's a range of variation in features, and a limited number of said features, so sure, there will be repeats of combinations, more or less. i mean, how many possible kinds of eyes? all are round or oval. no square, triangle, etc. all mouths: two lips covering teeth.
variations: width, color, placement (all eyes are placed above the nose, just under the forehead, tho, all mouths below nose and above chin, etc). and for something to stay roughly in a circle shape, the possibilities aren't infinite. ditto lip possibilities.
and so on.