This is what had happend. I had decided to delet my contacts in SIM card by using a app called contact2sim, and before I delet it, I had copied all my contacts to my phone AGAIN (I had done it before, I just wanna make sure that I had everyone in my phone). I then used contact2sim to delet my SIM . While I was playing around my contacts after I had deleted my SIM, I noticed that there were some double contacts (just some, not all of them). What's more strange is that none of the information of the double contacts appear to be true. ie. I had two John on my list, and when I tap into the faulty John, instead of showing John's information, it would show Jack's name and his info. I couldn't delet the faulty ones either. Everytime I tried to delet them, this message would pop up "the process android.process.acore has stopped unexpectedly. Please try again" These double contacts would appear in my phone and my SIM. please help, thanks.