If an object were able to go faster than the speed of light, it would indeed go back in time. Given the correct conditions it could possibly interact with its past self. This is one of the reasons why scientists don't believe anything can go back in time. If a future you came and interacted with you (perhaps harming you in some way!), very strange things could happen. How could a time traveler who could potential kill or otherwise incapacitate his past self then still exists in the future to travel back in time in the first place!