Not sure if this has been filed already, but I noticed on several blog posts comments were being reposted multiple times. It seems to happen to commenters logged in through OpenID.
I have just written my comment and after posting it was not shown under "comments". I then reposted it, because I thought that it had failed.
After the second post (which was not shown, too) I thought it would probably be a good idea to reload the page. I then saw that my comment was posted twice.. :-S
I've deleted your extra comment
I've also deleted the extra comments from the other two examples in the original post. But I'm not going close this ticket as there may be a lurking bug that needs to be investigated.
There isn’t a real bug in a sense such as page rebuilds failing to happen. The problem is that nothing happens that would invalidate the browser’s cache, so the browser doesn’t reload the page, so the comment (which is actually there) does not show up on the user’s computer without a manual refresh. I don’t know that anything can be done about this, given the way that MT works (i.e. writing out static files, whose headers, when being served, are under the control of Apache).