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

plugins/pidfield/pidfield.module

@@ -276,12 +276,15 @@ 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;
+}
 
 /**
  * Theme function for 'plain' example field formatter.