If a session is already saved and I start a new one, can I get the missing trophies? AC2?

well i wanted to know if in assassins creed 2 i could have a saved session and create a new one to get the trophies i missed for the first session? cuz i need the fly swatter trophy and i cant replay the memories on my first session so i wanted to create a new one to get the trophy. do they add up or a different trophy list starts?|||Yrah