Allow registered users to +1 a node more than once

I'm sorry to open this back up... But...

I recognize that this functionality isn't high priority. I could probably tweak the code myself if you could point me in the right direction. Where's the code for determining if a user can vote on a particular node or not?

If you could just point me in the direction of the vote validation code I'd be much appreciated.

Thanks.

Is it this bit o' code that prevents a second vote by a user?

if (!is_null($user_vote)) {
          $reset_token = drupal_get_token("votereset/node/$node->nid/$tag");
          $links['vud_node_votes_reset_link'] = array(
            'title' => t('Reset your vote'),
            'href'  => "votereset/node/$node->nid/$tag/$reset_token",
            'attributes' => array('rel' => 'nofollow'),
            'html'  => TRUE,
          );

I think it's the !is_null, right?

Should've read that better... IT's in vud.theme, right?

    // Do not allow vote with the same value
    if ( ($casted_vote > 0 && $value > 0) || ($casted_vote < 0 && $value < 0) ) {
      $value = FALSE;
    }

    if ($value !== FALSE) {
      $vote['value'] = $value;
      $vote['value_type'] = 'points';
      $tag = $tag ? $tag : variable_get('vud_tag', 'vote');
      $vote['tag'] = $tag;
      $vote['content_id'] = $content_id;
      $vote['content_type'] = $type;
      $votes = array(0 => $vote);
      drupal_alter('vud_votes', $votes);
      votingapi_set_votes($votes);
    }