problem with duplicate files in recordbox

Good afternoon. have a music collection, for example 8000 files. for batch processing in a third-party program (required to make capital first letters in the names of the tracks). after that I did add the entire library collection recordbox. and was not 8,000 files and 10,000.  if there was a file type "artist - title track" and became "Artist - Track Title" in the library recordbox came two files actually linked to the same file at the same time and both are reproduced from the recordbox. how to remove and why not record unites these files?