You don't need to check every platform. At present, there are many paper duplicate checking platforms commonly used in the market, and the duplicate checking algorithms and databases of these platforms are different, so the results will be different. If every platform is checked, first of all, time is not allowed, because it will waste a lot of time, and the duplicate checking results of different platforms may not be exactly the same, so you only need to select one or two platforms to check duplicates. Of course, you can refer to the advice of the school or tutor, or you can choose according to your own understanding and experience of the platform.