The names on the contributor list is taken directly from the names entered in the contributor field on each recipe. If you see what looks like the same name in your contributor list more than once, that is because the name in the Contributor field in some recipe(s) is different. You may not see it, but check for two spaces " " between first and last names - or a space at the end of a name. The software thinks it is a different person. The best way to see what recipes are affected, go to Index by Contributor. Scroll the list until you see the person that appears duplicated. They will be in this list more than once, too. Edit each recipe under all versions of their name and make sure the Contributor fields match.