Bug fix: transform re-assigning the value of a column was creating a duplicate column

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7-to-database-extension/trunk@946662 b8457f37-d9ea-0310-8a92-e5e31aec5664
Version: 2.8.1

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7-to-database-extension/trunk@946663 b8457f37-d9ea-0310-8a92-e5e31aec5664