We are unable to process this relationship because the parent and child products share the same SKU [%s]. For help with this error see http://sellercentral.amazon.co.uk/gp/help/23881
If you submit a tab-delimited inventory file, this error occurs when you submit identical values in the SKU and ParentSKU columns. A product cannot be a variation of or accessory to itself. To correct this error, enter different values in the SKU and ParentSKU columns before resubmitting your inventory file.
If you post a relationships feed (XML), this error occurs when a Relationship element in that feed contains a SKU value that is identical to the ParentSKU value. To correct this error, modify the SKU or ParentSKU values so that they differ.
For more information about creating parent/child relationships, please see Creating Parent/Child Variation Relationships.