It MIGHT be best as a blog, but if you cleverly masked it (as, say, a general "anyone produced any films?" thread or "anyone done any student films" thread, or something along those lines. Really, anything that was cleverly masked, and not completely blatant self-promotion), I don't see why not. I've certainly allowed people to do self-promoting in the past because it was subtle or cleverly done.
I have theory on why the system double posts: If one hits the post/save page button and it doesn't load right away, they may hit the button again, sending anothor post/edit to the thread/talk page. I have done this on both BP and here on the forums.