§ 17-a. Abandonment of claims under defective tax sales; recovery of taxes paid thereon by state. Where the claim of title of the state to any land is based on a tax sale, which title in the opinion of the attorney-general would be declared void by the courts, the commissioner of general services, on the filing with him of such opinion and the evidence upon which such opinion was based, may, by order, abandon any claim of title to such land, but, notwithstanding such abandonment, the people of the state shall have a lien upon the real property affected by the abandonment, prior and superior to all other liens, for the amount of all taxes, fees and charges admitted or paid by the people upon such real property to the date of the abandonment of the state's claim of title, together with interest thereon from the dates of payment. Provided such lien remains unpaid after the expiration of one year from the date of the abandonment, the people of the state may foreclose such lien as a mortgage on real property is foreclosed; but in any such action establishment of payments of taxes on said land or any part thereof by the adjudged or admitted owner of the property during any of the same years in which payments were also made by the people of the state shall reduce the lien of the people by the larger of the two tax payments for each of the years affected by duplicate payments, and in the event that wholly identical areas are not affected by the duplicate payments the court shall have power to apportion and adjust the amount of the lien as equity may require. This remedy for recovery of tax payments shall be in addition to any other remedy now or hereafter available in law or in equity, and shall be without prejudice to any defense or offset available to an adverse claimant in law or in equity.