Fix oscommerce link product

In the backend of our ecommerce software which is based on a heavily modified oscommerce core we have a error with the link product in the copy product page passworded: [login to view URL];pID=1475&action=copy_to when you go to copy and select link instead of duplicate you get this error: 1062 - Duplicate entry '0-0' for key 1 insert into products_groups (customers_group_id, customers_group_price, products_id) values ('', '', '0') [TEP STOP] I need the above problem fixed so that linking is functioning correctly.