Originally Posted by: CGTT 
It would be nice that the software allows me to select all duplicated songs in one click.
After I run I got more than 1500 duplicated songs. It would take too much time to delete all songs by clicking and scrolling.
Are you sure that the songs marked in blue color have bigger or the same file size with the duplicated songs marked in red color?
Thanks
Deleting songs is an irreversible operation and shouldn't be taken "blindly". "Select all and hit delete" will be abused by users and they will regret later. To clean up your collection, spend some time to make sure you are deleting what you want to delete - you'll feel confident afterward that your collection is at its best! I'll add a feature to "delete all red songs" in the next version.
You can verify the size by clicking on the song and see the size at the bottom-left. Go through a few songs to test, the blue versions should be the largest-size version.