Touch ID alone should suffice, identical twins have different fingerprints. Similar, but not identical. There's some amount of entropy captured in the womb which affects their development. [1]
> Fingerprints aren’t included in these genetic similarities. That’s because the formation of fingerprints is dependent on both genetic and environmental factors in the womb.
> The chances of identical fingerprints in identical twins is slim-to-none. While anecdotal articles online often discuss the possibility of a chance that the science could be wrong, no research has found that identical twins can have the same fingerprints.
> [...] As a result, identical twins may have similarities in the ridges, whorls, and loops in their fingerprints. But upon closer examination, you’ll notice differences in some of the smaller details, including spaces between ridges and divisions between branch markings.
> Fingerprints aren’t included in these genetic similarities. That’s because the formation of fingerprints is dependent on both genetic and environmental factors in the womb.
> The chances of identical fingerprints in identical twins is slim-to-none. While anecdotal articles online often discuss the possibility of a chance that the science could be wrong, no research has found that identical twins can have the same fingerprints.
> [...] As a result, identical twins may have similarities in the ridges, whorls, and loops in their fingerprints. But upon closer examination, you’ll notice differences in some of the smaller details, including spaces between ridges and divisions between branch markings.
[1] https://www.healthline.com/health/do-identical-twins-have-th...