On Mafia 2 for X-Box360, will loading a previous chapter erase all my progress?

[Alex]

I have completed the game, but now I want to go back and replay some of the chapters, but not the whole game, over again. When I choose to load a chapter a message pops up saying "Loading into a previously completed mission will erase all progress in the current mission and gameplay will resume at the beginning of the mission you choose to load. Are you sure you wish to load a previous mission?" This warning sounds as if I will lose all of my saved progress, but I can't believe the makers of the game would do something that stupid. So will I lose everything if I load? Thanks!