If you ask me the should be and also be a banable offence. After member creates their first duplicate thread they should be warned, then if they do it again they should be banished for all eternity!
Moderator, is it possible to merge duplicate threads? I know you do an excellent job of removing them if they haven't had any replies. I suppose if merging threads is a pain you could close the shortest thread and post a link to it in the other thread. Anyway my gripe isn't with you but with the morons who are responsible for duplicate threads.