Passaic County Judge Sohail Mohammad made the ruling Monday in a paternity case.
It's possible but rare for a woman to give birth to twins with two fathers. Mohammad says he found two other court cases nationally on such matters.
It can happen when the woman has sexual intercourse with two men in the same week, and an egg is fertilized by each.
It came to light when a Passaic County woman sought child-support payments from a man she thought was the father of her daughters, who were born in January 2013.
Paternity tests showed he was almost certainly the father of one but wasn't the father of the other.
He owes $28 per week.
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