Sibling Rivalry: The Olsen Twins Battle the Fanning Sisters on Dueling Magazine Covers

2011 is surely shaping up as the year of the sibling. It's as if every celebrity in town shook their family tree and raining down like leaves came a new generation of matinee idols and starlets. Beyonce has Solange, James Franco has Dave, and Princess Kate has Pippa. Now, Conde Nast's two biggest lady's fashion mags--W and Vogue--are featuring pairings on recent covers. For Vogue's special-edition "Best Dressed" issue, Mary-Kate and Ashley Olsen gaze out blankly from the cover with their doe-eyes. On W, it's the Fanning sisters, Dakota and Elle, who play etheral partners-in-crime. Let's play a quick game of Sophie's Choice, shall we? Were you forced to pick one pair to save and one to perish, which would you rescue?