It often happens that when a person is sick to the point of being close to death  he or she is given an additional name to "fool"  the angel of death. Thus, if a book is written immediately after the sickness the extra name may appear on the book.  However, often after the person is deceased the name is removed, and a book will appear with that extra name removed.
How shall the name appear in the authority and on cataloging?

The LCRI  22.3A on "fullness" states: " If the forms of an author's name vary in fullness from one work to another in the same language and the AACR2 form for the heading has not yet been determined, apply the following ..."

Thus, if the established heading that disagrees with the form of name on your item IS coded AACR2,  "and subsequently received items show forms in the chief source that vary in fullness, generally do not change the established heading" (a bit later in RI22.3A.

The RIs are really very much opposed to changing established AACR2 headings, for whatever reason.  If you feel that an established form, with or without the name added because of sickness, really NEEDS to be changed, you will need to make the case on other grounds than the 80% rule.