Nah, you would know it was different because it would be a new timeline that was different than the one you left. Time isn’t one line only, parallel paths can exist. If you leave one path and enter the past, it creates another that becomes different but separate from the first one. It doesn’t replace it.
If it didn’t create a separate timeline, it would be a time paradox like if you went back in time and killed your father. But then you wouldn’t exist and therefore couldn’t go back in time to kill your father.
