an additional amount as liquidated damages equal to the sum of the amount described in clause (i) and the interest described in clause (ii), except that if an employer who has violated
section 2615 of this title proves to the satisfaction of the court that the act or omission which violated
section 2615 of this title was in good faith and that the employer had reasonable grounds for believing that the act or omission was not a violation of
section 2615 of this title, such court may, in the discretion of the court, reduce the amount of the liability to the amount and interest determined under clauses (i) and (ii), respectively; and