This in essence creates a duplicate of the same resource across multiple NSs. Not very good if you are forwarding data at all. The examples of what can occur can be seen in each of the previous examples. One way to avoid this particular issue is to exclude resources which have been forwarded by another NS. This collection contains SQL code which will perform a lookup of resources located on the NS with those at the top level NS. If it finds a resource where the OwnerGUID is different with a more recent date then that correlates to another NS forwarding up a more recent copy of this same resource. You will need to edit the SQL to name your reporting/top level server. You can then use this collection within a filter to exclude these resources from being forwarded.