I am wanting to generate a list of duplicate isbns from our catalogue (so I can see which bib records need merging) - but only where they are duplicated at 2 specific branches. I have imported this report from the koha report library: SELECT GROUP_CONCAT(b.biblionumber SEPARATOR ', ') AS biblionumbers, b.title, b.author, GROUP_CONCAT(i.isbn SEPARATOR ', ') AS isbns FROM biblio b LEFT JOIN biblioitems i ON (i.biblionumber=b.biblionumber) GROUP BY CONCAT(substr(b.title,0,9),"/",i.isbn) HAVING COUNT(CONCAT(substr(b.title,0,9),"/",i.isbn))>1 I need restrict the report to just list items that are duplicated at 2 specific libraries. I tried to add WHERE homebranch=<<Owning branch|branches>> into the clause & ORed these together but I just get an array error message when I try to run it. How do I get the branch filter to work for this? Many thanks, Jeremy