views in D7 :: remove doubles in exposed filter list
The Views exposed filters block is a Drupal form, one that can be modified via a hook_form_alter or hook_form_FORM_ID_alter implementation. Here is a simple sample implementation of the more generic hook_form_alter.

/**
 * Implements hook_form_alter.
 */
function foo_helper_form_alter(&amp;$form, &amp;$form_state, $form_id = NULL) {
  if($form['#id'] == 'views-exposed-form-content-page') {
    // Do something with mah filters...
  }
}


If you are in doubt of what #id to use, you can always just implement this hook, go to your Views page, and watch the output of the $form variable to figure out what is the correct id to use. If you are in D7, the ID you are looking for will most likely be prepended with views-exposed....