Two Ottawa families are suing a well-known fertility doctor over allegations his clinic used the wrong sperm during their fertility treatments.

Trudy Moore and her husband Matthew Guest, as well as another patient, Jacqueline Slinn, are suing Dr. Norman Barwin and his Broadview Fertility Clinic alleging he used the wrong sperm and failed to tell them.

Moore and Guest allege in court documents that a blood test confirms Guest is not the father of their child, born in 2007 to a surrogate. They ordered the test after noticing their child did not resemble Guest, CTV's Daniele Hamamdjian reported Tuesday.

Slinn says a blood test also proves she was not inseminated with her chosen donor's sperm. She had her baby tested after trying to contact other women who had used the same donor and found her child's DNA did not match the other children's, Hamamdjian said.

"So here they are today suing Dr. Barwin for $3 million combined," Hamamdjian said. "They are asking that he be tested to rule out the possibility that he is the donor, and they want to know who the donor is in each of the cases."

Pam MacEachern, the lawyer representing both families, told CTV Ottawa that based on evidence she has heard, "we believe that it probably happened in other situations."

Barwin is one of the world's leading fertility doctors. A native of South Africa, he has practiced for decades and is a member of the Order of Canada.

While he is credited with helping thousands of families have children, this is also not Barwin's first brush with controversy. A decade ago, Barwin was caught cheating in not one, but two marathons. In 2000, he was caught cheating during the Boston Marathon, and in 2001 he was caught cheating during the Ottawa Marathon.

Dr. Art Leader of the Ottawa Fertility Centre said he doesn't believe Barwin's past problems and the most recent allegations are linked. Leader said he knows Barwin, and can't imagine he intentionally mixed up donor sperm samples.

"Dr. Barwin has always been a caring physician who has cared for his patients and has been dedicated to the care of the infertile," Leader said.

Barwin himself has not issued a statement about the allegations and continues to work at his Ottawa clinic. The families are also choosing to let their lawyer talk for them, for now.

"This is a very difficult time for them as you can imagine," Hamamdjian said. "They don't know who the father of their child is, and they might never know."

With a report from CTV Ottawa's Catherine Lathem