Britney and Jamie Lynn Spears showed off their bikini bodies in Miami Monday afternoon.

“They both looked to be in pretty good shape,” a witness tells Usmagazine.com of the sisters, who spent about an hour at the Mandarin Oriental Hotel pool Monday afternoon with their kids and parents.

See adorable photos of Britney and her boys

It’s the first time 18-year-old Jamie Lynn, who welcomed daughter…

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