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Sibling silliness: Prince Harry sports William mask during fun run in Brazil

Prince Harry donned a mask with his older brother's likeness during a mile-long Sport Relief run. "He thought it would be a bit of fun and give his brother a laugh. He hadn't planned to wear the mask but had spotted it on another runner and borrowed it," a royal aide told The Daily Mail. "It took everyone by surprise but he thought it was a real hoot and would make his brother laugh."

-- Reported by Us Weekly