I think it would be really cool if it turned out that it could tell the difference between some pairs of identical twins due to seemingly imperceptible differences.
I'm sure it's not 100%, but I'd bet it's close. Certainly by young adulthood the identical twins I've been around have been relatively easy to distinguish.
That's sort of my theory. But I wonder how much of people's ability to distinguish identical twins is based on physical differences vs more subtle things like how they carry themselves/interact with the world.
Some twins I've known deliberately create physical differences like different hairstyle so other people can recognize them easily without interactions.