The lothario strikes again!

After months of crushing on her, Wilmer Valderrama has added Minka Kelly to his list of conquests, a source tells Us Weekly.

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"They were kissing and grinding" at West Hollywood's Greystone Manor Supperclub March 18, says an onlooker of the That 70s Show alum, 32, and the Charlie's Angels star and Derek Jeter's onetime love, 31.

While Valderrama (ex of Lindsay Lohan, Mandy Moore and Demi Lovato) has been squiring Kelly around town -- to Disneyland in Anaheim Feb. 21 and L.A. eatery Pink Taco on March 15 -- the two aren't exclusive just yet.

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"I wouldn't say they're boyfriend and girlfriend," says a pal, "but he's started ignoring calls from some of his other girls."

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