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Eh, what else is new. The Art Basel convention in Miami drew in quite an A-list crowd this weekend, and plenty of drama to go with it!

The NY Post reports that Mary-Kate Olsen got into an argument on Wednesday night with Kirsten Dunst when the two sat together at the Audi party at the Delano in South Beach.

A source tells the Post, "They just kind of stared at each other for a long time and then started exchanging nasty words. Then Olsen just got up and left. She's been going really late every night." Another inside source says that Mary-Kate "looked like she had not brushed her hair in a week and she was chain-smoking the entire time and sitting like a sourpuss with her boyfriend. She was acting very oddly." Hmmm, wonder what bit Mary-Kate on the bum?

In other news, Basel organizers told X17online.com exclusively that Brad Pitt was there on Wednesday to snatch up some pricey art that he had recently purchased. Brad brought along buddy Matt Damon to check out the new goods, and then Matt jetted off to London to hang out with another famous pal, George Clooney.