Ok, so I just wanted to start a thread with a poll and here what happened: I wrote a message, chosen a poll started editing the poll, and then I decided I'll change the thread subject. I hit back button, changed the subject, clicked "continue" wrote a poll again and clicked "send". And guess what? Two threads - one with poll and one without were here. PS. Ah, and thanks for the infraction, mods here are fast. .
Not a bug... if you submit a new thread, hit back and submit it again, it will create 2 threads (same with any form).
You should've used the "Edit" button. The browser's back button doesn't use the server's back button. What you submit on the server has already been submitted...you can't go back on the server, that's why you have to edit it, because it was already submitted into the database.