A Fake Lady Gaga had the “little monsters” of Miami freaking out that they were in the presence of the real pop icon on Sunday. The imposter rolled up to Big Pink restaurant with four SUVs and a security detail of 10. Once her security did a sweep, the blonde look-alike enjoyed breakfast. The poor man’s Gaga then caused chaos at French Connection in South Beach, where, a spy said, “Salespeople flocked to assist her, even helping her try on clothes for 30 minutes. She was swarmed by fans screaming ‘Happy Birthday!’ ” And Guess rep Alina Hauptman sent a breathless press release complete with a photo of faux Gaga at their Lincoln Road store, saying, “The crowd was getting so out of control that security needed to shut down the store so Lady Gaga could browse . . . [she] purchased the Lucy Lace Skirt.” The real Lady Gaga was in Vegas, celebrating her 25th birthday by performing at the MGM Grand Garden.