That's the point. In my early years, I don't care so much about diferrent version and watermarks... But now, I deleted all the movies with Chinese watermark because of their bad quality. It's really annoying and terrible!
I used to delete them at a time, but this was annoying too.
I decided to move them to a specific folder, or to mark folders with watermark videos, so I know which ones would have to be re-downloaded later.