Type in the last name of a recipient, and the suggestions will show. Even though there is only one suggestion based on the name I type, when i click "tab" to accept the name the "To:" will be completed with two entries (same name, same email address). This happens with many people, but not all. And I've checked - there are no duplicate entries in the Contacts. Any ideas on how to fix? EDIT This only started a few months ago right after I installed Mavericks.