Quote Originally Posted by O'Callaghan View Post
One reason some names are on multiple sept lists is that people of that name in different geographical areas may have been affiliated with different clans.
....
"There is no official list of recognised septs. This is a matter for each chief to determine. But where a particular sept has traditionally been associated with a particular clan it would not be appropriate for that name to be treated by another clan chief as one of its septs."

The Court of the Lord Lyon, http://www.lyon-court.com/lordlyon/240.html

and that is that.