It can happen that you enter the same author under several different names (for instance if you made a typo or if you entered once the full name and another time only the name's initials).
With the authors index, you can find such inconsistencies easier. Moreover, BiblioMaker has a mechanism for merging easily entries for the same author :
In the authors file, isolate the different entries for the same author. Decide then which entry you will keep and which one you will delete.
Modify the entry to delete. In the author cataloguing template, click on the Trash icon in order to delete this entry. If this entry is linked to titles records, a warning is displayed : "There are x title(s) linked to this author. Do you want to link these titles to another author?". Enter in the "Replace with" field the author you want to keep, then confirm that you want to delete the other entry.
BiblioMaker replaces in the linked titles records the wrong entry with the right one, then deletes the wrong entry.
This mechanism is also available in the Series, Subjects and Class marks files.