Thats a very interesting concept. In time travel, the time traveler is the person with the most amount of unaccurate history in his mind. However, I believe that the traveler does return to his/her previos period but the regrouping of information around him is different. All timelines, time-periods and alternate realities exist as a wave of energy and information that only manifest as the traveler goes back. What I mean is that the only existing moment is present, for us in this present. When we move forward or backward that present is altered and manifested around us.