Trivia : We thought that biometrics was fool-proof

Came across this in a fast company article on computer security. I have copied the relevant text (don't know how long this link would work)

Sidebar: The Case of the Phony Fingerprint
As the furor over missed signals by the FBI and the CIA demonstrates, there's no shortage of ways in which humans can screw up security. And even the most sophisticated security system can't always defend against human foibles. Take the latest favorite gizmo of Sondra Schneider, the founder and CEO of Security University. A handheld biometric fingerprint-sensor and smart-card device, this gadget allows you to program your fingerprint in, keeping your system secure from access by anyone but you. Or does it?
Last fall, Schneider hooked up the gadget to her computer and scanned in her fingerprint. On her hard drive was a presentation that she was scheduled to deliver at Comdex, the big computer show in Las Vegas. But 20 hours before leaving, she accidentally grabbed the handle of a hot pot on her stove, searing her fingers down to the bone -- and destroying her fingerprint.
As luck would have it, Schneider has an identical twin. So she called her sister, who lives in San Diego, told her to hop on the next plane to Las Vegas, and hoped for the best. At the convention, her sister was able to log on to Schneider's computer, and the presentation was saved.
Her obvious take-away?"Companies should be sure to ask employees who have high access to knowledge inside an enterprise if they have an identical twin," she warns. Otherwise, they're a security risk."

I don't think that I even have to say anything.....

One nagging doubt though, isn’t the fingerprint supposed to be unique. I always thought that even twins would have distinct (non-unique) fingerprints. Does anyone know more? IMHO this could be the limitation of the related technology!