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It's not easy dating twins. Just ask Hugh Hefner.

The Playboy mogul admits he can't tell new girlfriends Karissa and Kristina Shannon apart.

See photos of stars with twins.

"I have one little trick, one has a little mark [on her neck]," Hef told Fox News at a recent Playmate of the Year party. "Other than that, I don't know."

Check out Hef and the girls' wildest times at the mansion.

Hef split from Bridget Marquardt, Holly Madison and Kendra Wilkinson in October, but they remain on good terms.

Pregnant Wilkinson and Hank Baskett are saying "I Do" at the mansion in two weeks. Their baby could end up a familiar face at the grotto as well, Hef says.

Look back at all of Hef's women.

"I'm sure the the baby will end up at the mansion. We do have [lots of little bunnies]," he said. "We have a lot of friends and second generation Playmates, so there are a lot of kids around the mansion these days."