Created attachment 149122 [details] Different subject heading in same authority record Koha doesn't take diakrits in consideration when authority records are created. In swedish we have three extra letters in the alphabet - ÅÄÖ. Koha treats those letters as AAO, and creates one unified authority record for the subject headings "Ankor" (ducks) and "Änkor" (widows) So, if you search for widows as subject you will get matches for Donald Duck.
I assume this might be because it appears the same to the search engine/SQL. Maybe an additional check is needed before creating the authority.