Of course, if the system actually uses a resolution that accurate, it's quite likely you won't even be your own doppelganger. Retaining water would be enough to throw it off.
I'd wager that evolution and neural net learning has struck a pretty optimal balance between false positives and false negatives for this in the human brain.
Oh, and the human system definitely uses measures the researchers didn't take in this study; ever failed to recognize someone because they're not in the same context you usually see them? Heck, I once spent 2 hours on a train talking to someone I thought I sort of recognized. A day later I realized I'd been talking to a (former) CEO of one of the biggest companies in the country, but of course, I wasn't exactly used to seeing him outside TV or newspapers. Ah, well, at least he got an early insight into free software.