My brother (not a twin, physically very different from me) once came with an HP laptop with fingertip unlock, and my finger unlocks it ~ 50% of time.
I suspect those system to be set with an extremely high level of tolerance; if they aren't, they probably often fail to recognize legitimate fingerprints and people revert to the old, not-hardware-vending passwords.
It'd be interesting to benchmark this trick against commercial grade systems.
The hardest part of finger print analysis is not the matching but figuring out if the finger is still attached to the body that it originally came with, and then if the print is still attached to the original finger.
I'm sure they are; most of the time they're not guarding national security, but a few soccer moms and football fans complaining they can't get into their laptop because their fingers still have Cheetos on them could be a PR problem.
I suspect those system to be set with an extremely high level of tolerance; if they aren't, they probably often fail to recognize legitimate fingerprints and people revert to the old, not-hardware-vending passwords.