Sienna Miller was out again yesterday for another afternoon of rehearsals for After Miss Julie following her evening out at The September Issue premiere on Wednesday. She attended the screening alongside Anna Wintour, who apparently had a few of her famous guests — including Diddy — on their best behavior. It looks like Sienna sightings will be a regular occurrence as she gets ready for her Broadway debut, but she will be making a quick trip back to London soon. She and her sister Savannah have their second-ever presentation of their twenty8twelve line scheduled for the city's upcoming Spring Fashion Week.

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