I must have played with a friend who was further than I in the campaign at some point because I just recently reached a point in the game where I was asked this question;
Do you wish to skip over the missions you've completed in other play sessions or continue as normal?
I chose to continue, as I can't remember anything I've done with anyone else, its been too long. No problems, except about 5 minutes later I accidentally moved ahead too far, too fast, and skipped some dialogue I actually wanted to hear.
To solve this issue, my plan of action was to end-task to skip the auto-save process, and redo the mission and listen to the dialogue. Upon starting the game up, instead of starting at the beginning of the mission, I started at what I think is the end of all the missions it originally asked if I wanted to skip.
Is there any way to fix this? I'm playing on PC.