function track_validate_file

The upload gpx file validation fails with IE. (IE uploads filname.gpx.txt?)
There is a ereg_replace going on in track.module:
if ($file = file_check_upload('file')) {
$ext = strtolower(ereg_replace("^.+\\.([^.]+)$", "\\1", $file->filename));
if ($ext != "gpx") {
Does this remove everything but the extension and check that it is gpx?
This check should also remove all non English letters from the filename and check if the filename contains .txt in front of .gpx or else the possessing of the gpx file fails.