I am cataloging a new collection on a new install of Koha (3.03.00.019) and have BiblioAddsAuthorities set to 'allow'.
I added a bunch of books with the same author and found that Koha created an authority for the author for each book (lots of dups). I went into some of the bib records and edited the author by using the authority search and choosing to link the bibs to the same authority. None of these bib records updated - they are all still linked to the authority that they created. I tried this on several titles and rebuilt both the authorities and the bib indexes - no change.
This was one of the issues fixed in bug 7284.
*** This bug has been marked as a duplicate of bug 7284 ***