Section 181.51 - Prevention of improper payment of claims(a)Double payment of claim. The drawback claimant shall certify to Customs that he has not earlier received payment on the same import entry for the same designation of goods. If, notwithstanding such a certification, such an earlier payment was in fact made to the claimant, the claimant shall repay any amount paid on the second claim.(b)Preparation of Certificate of Origin. The drawback claimant shall, within 30 calendar days after the filing of the drawback claim under this subpart, submit to Customs a written statement as to whether he has prepared, or has knowledge that another person has prepared, a Certificate of Origin provided for under § 181.11(a) of this part and pertaining to the goods which are covered by the claim. If, following such 30-day period, the claimant prepares, or otherwise learns of the existence of, any such Certificate of Origin, the claimant shall, within 30 calendar days thereafter, disclose that fact to Customs.