Backup files duplicated

I moved some files from one folder to another one in my PC, then started backup from my PC to WD MY PASSPORT. However, when I checked the files in MY PASSPORT, I found the files were duplicated in both folders, it means the backup tools added the files to the new folder but didn’t delete the files in previous folder. The problem is it occupy the space in MY PASSPORT and which is unnecessary. What should I do to avoid the duplication when moving files between folders?

@aarontong How did you move the files? Did you cut and paste, copy and paste or drag and drop?

https://lifehacker.com/5801525/help-new-pc-users-learn-how-to-copy-cut-and-paste

You can find more about each way if you do a Google Search or use your favorite search engine.

Drag & drop, so the files do not exist in the previous folder but be moved to the new folder.

To do that, so they no longer exist in the old folder, you should cut and paste.

Here is an image of me drag and dropping a movie to my Public folder on my My Cloud. This does not remove the movie from it’s original location.

I tried cut & paste this time, but still can’t fix it. After backup both folders from my PC to MY PASSPORT, I checked the files still exist in both folders in MY PASSPORT.