Ticket #16951: reg_tx_for_otype-no_dupes.patch

taxonomy.php

@@ -437 +437 @@
         if ( ! get_post_type_object($object_type) )
                 return false;
 
-        $wp_taxonomies[$taxonomy]->object_type[] = $object_type;
+        if ( ! in_array( $object_type, $wp_taxonomies[$taxonomy]->object_type ) )
+                $wp_taxonomies[$taxonomy]->object_type[] = $object_type;
 
         return true;
 }