It's important to note that this is a small sample of people, and that the host PC (a Lenovo Yoga 3 14) had a sophisticated depth-sensing camera. There's still a chance that the right set of twins could dupe the Hello system, or that another camera might not be so smart. However, this suggests that Windows' face detection is reliable enough to eliminate some of the frustrations you see elsewhere. And that's important for both security and convenience. It not only prevents impostors from getting in, but reduces the chances that you'll have to jump through hoops to verify your identity. I'm a non-identical twin, and I find it annoying when people have problems tagging me correctly on Facebook -- in theory, Microsoft's technology should make my life that much easier.