19 CFR 182.51: Prevention of improper payment of claims.

(a) Double payment of claim. The drawback claimant must certify to CBP that the claimant 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 must repay any amount paid on the second claim.

(b) Preparation of Certification of Origin. The drawback claimant must, within 30 calendar days after the filing of the drawback claim under this subpart, submit to CBP a written statement as to whether the claimant has prepared, or has knowledge that another person has prepared, a certification of origin provided for under § 182.12 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 certification of origin, the claimant must, within 30 calendar days thereafter, disclose that fact to CBP.