No, an HTTP redirect. You can use the [header()](http://php.net/header) function to send http headers with PHP.
This way, you can get the info from the form, store it (probably in your session), and then redirect to the same page to send your response. Since you never send a body response to the *actual* form submission, the user’s browser won’t store it in its history (and so, can’t submit the form again on refresh/back/etc.).