Any order made by the secretary of labor as to a minimum wage or a standard of wages shall be deemed prima facie reasonable and just, and if the minimum wage or standard of wages shall be in excess of the wages theretofore paid in the industry, employment, utility or common carrier, then and in that event the workers affected thereby shall be entitled to receive the minimum wage or standard of wages from the date of the service of summons or publication of notice instituting the investigation, and shall have the right individually, or in case of incorporated unions or associations, or unincorporated unions or associations entitled thereto, collectively, to recover in any court of competent jurisdiction the difference between the wages actually paid and the minimum wage or standard of wages so found and determined by the court in such order.

It shall be the duty of all employers affected by the provisions of this act, during the pendency of any investigation brought under this act, or any litigation resulting therefrom, to keep an accurate account of all wages paid to all workers interested in the investigation or proceedings. In the event the order shall fix a wage or standard of wages which is lower than the wages theretofore paid in the industry, employment, utility or common carrier affected, then and in that event the employers shall have the same right to recover in the same manner as provided in this section with reference to the workers.