The memories we keep of ourselves are continually shaped by our retelling of them. We may not realize it, but events as we know them probably never happened in the way we think they did. Each time we run a particular file in our backup, something is disturbed as the connection is made yet again, and that memory will not be equal to the one that stood there before.
Ted Chiang has a short story about this his anthology book Exhalation. It’s about a world in which people have the option of recording everything that ever happened to them in a Life Log, and recalling events instantaneously as needed. This, of course, is not without consequences: causing stress on weak relationships when arguments are settled with recourse to hard facts.