Folder renaming

Yesterday I renamed my music subfolders in batches, correcting

Miles Davis-Kind of Blue

to:

Davis, Miles-Kind of Blue

by using the id3 tags for artist-album. I did hundreds of them. I liked it so much I bought a license, and now it is not working for me for another directory on the same HDD. It says error possibility of duplicate file name. All files have tags, I have permissions set correctly, and it just is not working any more, even though nothing has changed in my machine. I am running Win 7, btw.

Please help, as this is the sole reason I bought the program for. - I do not understand why it worked yesterday but not today

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