A US couple are suing a fertility clinic, saying the company implanted their embryo into a different woman.
The woman gave birth to twins in March, only for DNA tests to allegedly show the babies were not related to her or even to each other.
Anni and Ashot Manukyan have now taken custody of one of the children.
Both the Manukyans in California and the unnamed couple in New York who gave birth to the babies are suing CHA Fertility Center.
The company has not yet commented on the lawsuits.
"CHA robbed me of my ability to carry my own child, my baby boy," Anni Manukyan told a press conference. "Who wants to meet their child in a lobby of a hotel?"
The second baby boy allegedly comes from the egg and sperm of a third, unrelated couple. Court filings reportedly say the birth couple ceded custody of the child, and that the clinic has made contact with his biological parents - although they have not come forward publicly.
The New York couple - identified only as AP and YZ in the lawsuit to protect them from "embarrassment and humiliation" - gave birth to two boys who were not of Asian descent, as they are.
Earlier signs during the course of the pregnancy also suggested something was wrong. Scans showed they were giving birth to boys, despite doctors saying they had used female embryos.
Ms and Mr Manukyan had unsuccessfully gone through IVF in August 2018 using an embryo they thought was theirs. The pair say they were then asked to take a DNA test after the birth of the twins in March.
Their lawsuit says the couple then discovered "much to their horror" that their son had been "implanted into a stranger that later became his birth mother".
The couple then had to fight in the courts to reclaim their child, after the birth couple gave him up.
"What about the woman, you know? What is she going through right now?" Ms Manukyan told broadcaster CBS News. "Thank God we got our child back but she ended up with nothing."
The California lawsuit alleges negligence and emotional distress, as well as claiming CHA Fertility broke a state law preventing the use of embryos for any purpose other than that consented to by the provider.
Conviction on that charge could reportedly carry a prison sentence of between three and five years.
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