How to clean up the folder structure - duplicate author folders

Hi,
I have many cases in my books folder structure where there are two or even three folders for the same author. Typical variants are FirstName LastName vs. LastName, FirstName or LastName_FirstName.

It probably comes from transferring the library to a new computer a few times and forgetting to set it up exactly the same way (or believing the settings get transferred as part of the DB). It's not a big issue because in the GUI the books show correctly but I like my file system clean - and occasionally I need to copy a file and surprise, the book is not where you would expect it.

Is there a way how to change the variants to the current setup without deleting the books and reimporting them? (Just in case I have not been clear: I have 3 books stored in folder "Hemingway, Ernest" and 2 books in "Ernest Hemingway". I want all books in the former one.)

Thanks