Drupal 8: Preprocess hook to avoid duplicates

gistfile1.txt

/*
 * Implements hook_preprocess_HOOK().
 */
function rest_views_views_pre_render(&$view) {
  if ($view->storage->id() == 'articles') {
    $matchedGroupIds = array();
    foreach ($view->result as $row) {
      $id = $row->_entity->id();
      if(!in_array($id, $matchedGroupIds)){
        array_push($matchedGroupIds, $id);
        $rows[] = $row;
      }
    }
    $view->result = $rows;
  }
}