Don't render PID field unless a pid is present, as it displays the default collection object.

plugins/pidfield/pidfield.module

@@ -276,11 +276,14 @@ function theme_pidfield_formatter_default($element) {
   //return $element['#item']['safe'];
   $pid = $element['#item']['safe'];
 
+  if(!empty($pid)) {
     module_load_include('inc', 'fedora_repository', 'api/fedora_item');
     $item = new Fedora_Item($pid);
 
     return fedora_repository_get_items($pid);
     //return $item->objectProfile->objLabel;
+  }
+  return null;
 }
 
 /**