We've added a couple layers of protection to keep commenters from submitting their comment multiple times.

This happened most frequently by accident, when the system didn't appear to respond to the submit button, so the commenter just kept clicking. (Hey, if it didn't respond the first six times, maybe if I just keep on clicking it eventually will!) The problem was exacerbated by a missing database index (now fixed) that caused comment submission to be slow on sites with lots of comments.

We now have in place two layers of protection:

• The JavaScript for our standard comment form now disables the submit button after it has been clicked. Note that if you aren't using our standard code, this is up to you to set up, but if you use our comment code and include jQuery and our form.js file, then it's all set for you.
• On the server side, if we see sequential submission of identical comments, we ignore all but the first one.