Technical problem with the new layout
I write a new post to one of the categories. I hit Post. I hit Refresh to see my post as it looks to the world. At the top of the page is an open text box with the post I just wrote, and beside it is a Post button. I think I must have not posted it correctly, and hit the Post button. Now there are two identical posts on the page. Surely this is not how it's supposed to work.
That doesn't sound like it's what should be happening.
When you start a new discussion thread, after you hit 'post', you should be taken to that discussion thread -- you shouldn't have to refresh it, and you should no longer be on a page that has an option to directly start a new thread.
If you're replying to an existing discussion, after you refresh, the reply box under the original post should be closed and empty.
Is it possible you're running a browser extension designed to save your text in case you accidentally close the page or navigate away from what you're writing? One of those might be reinserting the words in the text box when you refresh.