While on routine patrol, I was dispatched to a suspicious person at a local restaurant. When I arrived, I noticed a male adult sleeping in the back parking lot. I approached the male subject and announced my arrival. The male subject became startled and said he would move on. I asked him to sit down so I could ask him a few questions. I asked him if he had any identification, he reached into his wallet and handed me a California Identification card. I relayed the information to our dispatch. As one would expect, he had a warrant for his arrest. He was taken to the local jail to be booked for the warrant. During the booking process, the male subject was confused as to what his social security number was. It became apparent that something was not quite right. Upon further investigation, the male subject had another California Identification card in his wallet. This I.D. card turned out to be his real identity (the other I.D. card belonged to his brother; the reason the photograph and descriptions where similar.) I contacted my dispatcher and advised her of the correct I.D. for the person in custody. A few moments later, dispatch indicated the subject in custody was clear and had no outstanding warrants. So, I intern gave him the good news first. I explained that he had no outstanding warrants for his arrest. Now the bad news… I explained to him that he was being charged with providing false identification to a peace officer.