Having same surname does not logically equate that you can cheat
as the "same" person.
One could be fat, one could be thin.(Same surname does not equal
looking alike)
The only way you can cheat and not get caught is if you had a
twin who looks exactly like you.
After all, that's the only way they can verify that the pic on
your ID card is the same person as you. 
So simple twins cannot have same fingerprint.
They should do a fingerprint scan.