No more than two witnesses may be subpoenaed to prove single material fact; liability for fees of such witnesses; one fee for day's attendance

No district attorney shall direct that more than two witnesses be subpoenaed for the State to prove a single material fact, nor shall the State or defendant in any such prosecution be liable for the fees of more than two witnesses to prove a single material fact, unless the court, upon satisfactory reasons appearing, otherwise directs. And no witness subpoenaed in a criminal action shall be paid by the State for attendance in more than one case for any one day.