Possibly a quick fix.

Greetings, 

I've a single table which, among others, has order number and shipment number columns. An order can have multiple shipments but a shipment can have only one order. Unfortunately there have been data entry errors. In order to cleanse the table, I need to 

1)find all shipments which are shown to have more than one order number. 

2) find all orders which have the same distinct shipment assigned more than once.

Could you kindly suggest a solution. Thanks in advance.