When in admin overlay, submitting form over 400 times
Not sure what is exactly causing this, but maybe you can use a static variable as a workaround for this issue.

function mvp_form_test_test_form_submit($form, $form_state) {
  $sent =&amp; drupal_static(__FUNCTION__);
  if(!$sent) {
    watchdog('mvp_form_test', 'Form submitted with text '.$form_state['values']['sometext']);
    drupal_set_message('Form submitted with text '.$form_state['values']['sometext']);
    $sent = true;
  }
}