I had this from the minute I edited the text file to unlock all factions... don't know how it's there either. I read a post somewhere of someone who copy pasted the entire campaign and had an option in the provincial campaign for julii or something, so that it would suggest that if one could put an additional campaign in the folder where the imperial one is, it pops up in the provincial campaign screen.
But we'll only know for sure if somone has another campaign ready