SECTION 22. That nothing in this Act shall prevent the carriage, storage, or handling of property free or at reduced rates for the United States, State, or municipal governments, or for charitable purposes, or to or from fairs and expositions for exhibition thereat, or the free carriage of destitute and homeless persons transported by charitable societies, and the necessary agents employed in such transportation, or the issuance of mileage, excursion, or commutation passenger tickets; nothing in this Act shall be construed to prohibit any common carrier from giving reduced rates to ministers of religion, or to municipal governments for the transportation of indigent persons, or to inmates of the national homes or state homes for disabled volunteer soldiers, and of soldiers' and sailors' orphan homes, including those about to enter and those returning home after discharge, under arrangements with the boards of managers of said homes; nothing in this Act shall be construed to prevent railroads from giving free carriage to their own officers and employees, or to prevent the principal officers of any railroad company or companies from exchanging passes or tickets with other railroad companies for their officers and employees; and nothing in this Act contained shall in any way abridge or alter the remedies now existing at common law or by statute, but the provisions of this Act are in addition to such remedies: Provided, That no pending litigation shall in any way be affected by this Act: Provided further, That nothing in this Act shall prevent the issuance of joint interchangeable five-thousand-mile tickets, with special privileges as to the amount of free baggage that may be carried under mileage tickets of one thousand or more miles. But before any common carrier, subject to the provisions of this Act, shall issue any such joint interchangeable mileage tickets with special privileges as aforesaid, it shall file with the Interstate Commerce Commission copies of the joint tariffs of rates, fares, or charges on which such joint interchangeable mileage tickets are to be based, together with specifications of the amount of free baggage permitted to be carried under such tickets, in the same manner as common carriers are required to do with regard to other joint rates by section six of this Act; and all the provisions of said section six relating to joint rates, fares, and charges shall be observed by said common carriers and enforced by the Interstate Commerce Commission as fully with regard to such joint interchangeable mileage tickets as with regard to other joint rates, fares, and charges referred to in said section six. It shall be unlawful for any common carrier that has issued or authorized to be issued any such joint interchangeable mileage tickets to demand, collect, or receive from any person or persons a greater or less compensation for transportation of persons or baggage under such joint interchangeable mileage tickets than that required by the rate, fare, or charge specified in the copies of the joint tariff of rates, fares, or charges filed with the Commission in force at the time. The provisions of section ten of this Act shall apply to any violation of the requirements of this proviso.