I've logged it as a problem myself but it need Shaun to flick a switch I'm afraid.
In the meantime I've noticed that lots are deleting their duplicate posts, as they create them so thank you very much, though you can't delete duplicate threads, we'll try to do those as we go along.
I've been pausing after hitting the post button and then opening a new window to check to see if it has worked, but it is a bit of a pain, and some duplicates seem to happen even then!