A duplicate behavior was inserted when I updated the "Insert Behavior" on this page. I had the window opened in Split mode, when I selected the Insert Behavior for editing, it correctly highlighted the existing code. After modifying the insert (a new field was added to the database "is_parent") I updated the Insert to put a value of "N" in that field and the duplicate code was inserted immediately after the <!-- InstanceBeginEditable name="MainContent" --> template tag.