She said staff were surprised about the incident and the clinic had changed its identification procedures to prevent it from happening again.
Previously, formal identification was not required if the mother and father came to the clinic together, she said.
"Historically we have always allowed three people to identify each other, but obviously that was not a good thing to do and we don't do that anymore."
Now, everyone must provide a photograph and, if possible, some form of identification.
"In that particular situation, had they all brought in photographs there would not really be a problem because the photographs could be viewed by the appropriate authorities.
"Now we require photographic ID; at minimum they have to absolutely bring in photographs."
Under the Family Proceedings Act 1980 - which covered paternity tests - DNA clinics were not legally required to ask for identification.
Department of Internal Affairs spokesman Michael Mead said there had been one other case where a parent provided false DNA tests to alter a birth certificate. He would not provide any details due to privacy reasons.
"Ryan" told the Herald on Sunday DNA Diagnostics had helped him fix the situation, but the same could not be said for the Department of Internal Affairs.
"Births, Deaths and Marriages were calling me a liar - even though I had proof they made me go through the courts to get a court order saying she lied. DNA Diagnostics bent over backwards to help me. They fixed all their systems to make sure it never happens again."