The names of the several public utilities which are parties to any joint tariff, rate, fare, toll, contract, classification or charge shall be specified in the schedule or schedules showing the same. Unless otherwise ordered by the commission, a schedule showing such joint tariff, rate, toll, fare, contract, classification or charge need be filed with the commission by only one of the parties to it, provided there is also filed with the commission, in such form as the commission may require, a concurrence in such joint tariff, rate, toll, fare, contract, classification or charge by each of the other parties thereto.