Sometimes when I post a quick reply, I get the error message "This forum requires that you wait 10 seconds between posts. Please try again in 9 seconds.", I am placed into Advanced Edit mode, but the post has been made so if I wait the 9 seconds and hit Post I get a duplicate message. Site bug? I'm sure I'm not doing anything wrong.... I'm certainly not double-clicking the Post button (usually use Tab Enter in fact).
Will look into this on my local PC and see if I can recreate the problem. Normally I also use Tab Enter but as I have 10 sec restriction off may not have seen this.
Just got it again. I think if I had pressed Post Quick Reply then something else, then Back would take me back to the thread with my new message incorporated. As it is, Back takes me to the thread without my new message, just an empty edit box with the conversation as it was. (My update wasn't lost though; refreshing the page redrew the conversation with my update in)