On the page WAVT_Scripts_PHP.php it has code that automatically adds querystring variables to the end of the url. It is on lines 64-70. You could probably comment out that code, or better yet create a copy of the function and add it to your page so that you can comment out a local version and don't need to update the central include.
It is sometimes necessary to maintain the url parameters on update pages, so it is done automatically. I hesitate to have you remove it from the global function in case you ever use validation on an update page. Also reapplying the server behavior would overwrite the file.