Mario Lopez has been two-timing his girlfriend and “Dancing with the Stars” partner Karina Smirnoff with a 21-year-old Hooters bombshell.

The ENQUIRER has learned exclusively he’s been seeing Karina behind his new gal pal’s back.

Meaghan Cooper, an aspiring singer from San Antonio, Texas, and Miss September in the 2007 Hooters calendar, revealed to The ENQUIRER that Mario told her his romance was over with Karina.

“He said he broke up with her,” Meaghan told The ENQUIRER in an exclusive interview. “If he’s still seeing her, he said it’s because he’s just trying to keep things ‘cordial’ between them because of the dancing show. I wouldn’t be parading around with him if he was still with Karina.”

Meaghan claims, “I never would have gone to New Orleans with him if he said his relationship with Karina wasn’t over.”

But Mario may have been telling the Hooters beauty one hoot of a story. We found photos of Karina and Mario together on three separate occasions in the days following his weekend in New Orleans with Meaghan. On May 22, Mario was spotted leaving a “Dancing with the Stars” party with Karin in L.A.; on May 31 the two were photographed together at the Blackberry Curve Launch Party at the Regent Beverly Wilshire Hotel. The next day, Mario and Karina were snapped arriving at the ALMA Awards in Pasadena, California.

A friend tells The ENQUIRER, “Mario may be keeping up a public image as Karina’s boyfriend but he’s totally smitten with Meaghan. He’s been lusting after her ever since they met in L.A. when she was 18 years old.

Meaghan confirms, “I had a steady boyfriend at the time, so I didn’t date Mario, but I kept in touch. He called me recently and we’ve been seeing each other.”

She also tells The ENQUIRER that after their weekend in New Orleans, he asked her to go to New Mexico with him.

“He also wanted me to go to North Carolina, but I couldn’t take off on just two days notice.”

She also says she could be his escort to the upcoming wedding of Eva Longoria, and Tony Parker. She explains, “He’s been friends with Eva for 20 years, and I’m friends with Tony. So if he asks me to go to the wedding, I would.”

Meaghan doesn’t harbor any illusions about walking the aisle with Mario someday. “I would never get serious with him because he has a history of not being real faithful.”

(Brought to you by The National Enquirer)