A New Jersey court has ordered a man to pay child support for just one twin, after DNA tests showed that the second baby had been fathered by someone else.
The extremely rare case arose when the woman, identified only as T.M, applied for public assistance and named her current boyfriend as the father of the twins.
The revelation prompted a paternity test, which showed that each man was the father of one of the twins, who are now toddlers.
The original partner, identified as A.S. was ordered to pay child support to one of the children. He must now pay $28 (£18) each week for his daughter.
This unlikely process, known as heteropaternal superfecundation, occurs when a woman has sexual intercourse with two men during the same menstrual cycle, having released two eggs. One egg is then fertilized by each man.
The ruling, made by Passaic County Judge Sohail Mohammad, is thought to be one of only a handful of similar cases across the United States.