OS X :: Itunes Still Remember The Filename?

I imported some movies into itunes library. But the names of those movies are disordered and confused, so i try rename them to make the style clean.

Since there are a lot of them, i write some python code to do the work. I rename them directly from the source directory which is in iTunes/iTunes Music/Movies. But when I open itunes, the names are not changed. Then I try to use organize library option those names in the source file are changed back to old names.

After that, I move all those movies to other directory, and delete them in itunes. I try to rename those movies in that directory, and then import them to itunes. Surprisingly, when importing to itunes, they all changed to old names! I don't know why itunes still remember them.