I've noticed that over time there have been different rules for time travel. For example, originally the grandfather paradox was dealt with by the grandson either disappearing from the timeline or some other paradox set up. Now days, it seems more and more stories are using alternate timelines (like in Terra Nova). (And in the grandfather paradox stories, I don't think I ever saw one where, after the grandson disappeared, he wasn't there to cause the paradox, so he re-appeared only to disappear, then reappear in a loop.)
While every author or movie or TV show may have different rules, some seem to be standardized.
I've noticed one of these rules is conflicting memories. For example, when Marty McFly goes back in time and changes his present, he comes back, but remembers things as they were before he left -- he does not have memories of the changed events everyone else experienced. And, of course, those who didn't go back have only the memories of the new path and don't remember what Marty remembers. (I have yet to see Back to the Future II so I hope I'm not omitting anything.)
In Star Trek, with multiple time travel stories, people either remember the changed timeline or the original, but not both.
Is this rule ever broken? Are there stories where people have conflicting memories of an original and a changed timeline at the same time?