Copyscape is far from a perfect tool ... it simply searches for blocks of matching text. There is not a lot of intelligence behind it, you still have to determine if the level of duplication is acceptable or not.
That said it is the best/only tool available for free online that does this efficiently.
You can accomplish the same task manually by searching for quoted sentences in Google and then look for progessively smaller phrases until you are satisfied that duplication does not exist. |