You'd think that someone would have sent you a memo on lip syncing after the Milli Vanilli incident. If you decide to lip sink, it automatically gets out. And sure enough it did. Lin Miaoke, the little girl on the left was selected to 'perform' at the last minute because Yang Peiyi, the little girl on the right, was deemed a good singer but not cute enough to put on stage.
Apparently this last minute change was at the behest of one of these fine-looking fellows from China's Politburo.