Reality show creators swap barbs in copyright lawsuit.

Seen this show before?

The producers of "Trading Spouses: Meet Your New Mommy" are asking a U.S. District Court judge to throw out a copyright infringement lawsuit filed by the makers of "Wife Swap."

Fox Broadcasting Co., along with "Trading Spouses" creators Rocket Science Laboratories LLC, say they did not copy the plot of "Wife Swap," which first aired in the United Kingdom in 2003.

The duel began last year when "Wife Swap" producer RDF Media Ltd. filed suit against Rocket Science and Fox Broadcasting, a unit of News Corp.'s Fox Entertainment Group Inc.

"Wife Swap" began airing in the United States during the fall 2004 season on ABC. The show features two distinctly different families who trade wives for two weeks at a time. In the first week, the wives follow the rules of the other family; in the second, they change things according to their own rules back home.

In "Trading Spouses," which first aired in July 2004, two families swap wives in a similar type of interaction. At the end of the show, the traded wife receives $50,000 in cash.

"Defendants grossly overstate the significance of the $50,000 gimmick that was obviously grafted onto 'Trading Spouses' to create the illusion of material difference," said RDF.

Further, the suit claims, both shows use a male narrator, prohibit communication between the swapped spouses and their own families, have similar graphics in the opening narration and focus on the "extreme differences between the paired families." A lawyer for Fox and Rocket Science, Robert Rotstein, did not return calls.