In both armies each company had five sergeants, a First, or Orderly Sgt., he was as noted, the mustering sergeant and leading company NCO.

The other four "Duty" sergeants were assigned to the four sections of the company which was divided into two platoons
i.e., two sections per platoon.

Within each section were two ranks, approximately 10 men in each. In the Confederate army, four corporals were assigned, the Federal army had eight, apparently one per rank, two per section.

I do not believe there was a difference in duties of these
four Duty sergeants. Perhaps, they were assigned to the four sections which were designated in company line per Hardee, 1-4.

George Martin

William Watson describes his position of First (Orderly) Sergeant of his Baton Rouge Rifle Company:

He held the rank of sergeant major; his pay was equal to one-and-a-Half that of the first duty-sergeant. He was the general executive Officer of the company. He was secretary of the company and allowed a clerk. He went on no special detachments, or guard duty, except in cases of emergency. He kept the roll-book, and all other books, papers or accounts of the company. He was accountable for the men present or absent. He returned every morning to the adjutant a report of the state and effective force of his company. He made out all requisitions for rations, ammunition, arms, or camp equipage, and all other requirements. He had charge of all the company property, and reported on its condition. He inspected the tents and company camp ground, and saw that it was properly formed
and ditched, and inspected the sanitary arrangements. His signature must be first, and followed by that of the captain, on all company requisitions and reports. He called the roll at reveille, and noted absentees and delinquents, punished for slight offenses, and reported more serious offences. He gave certificates to men who wished to apply for leaves of absence. He detailed all men for guard, and
detachments for special service, and appointed police guards for the day. He reported the sick to the surgeon and saw them attended to. He marched up to the colour line, and handed over to the Adjutant all details for special service and guard duty. He drilled all squads, and the company in the absence of the commissioned officers. He took the place on the right of the company, and acted as guide. He went to the front and centre at parade and heard the orders read. When in front of the enemy, he was generally informed privately of the programmed, and of the movements to be made. While the duty sergeants were designated by their respective names as Sergeant T. or Sergeant H., he was designated as the sergeant, and was regarded as the ruling power of the company when on active service. [Life in the Confederate Army, Being the Observations and Experiences of an Alien in the South During the American Civil War, William Watson, Louisiana State University Press,1995, pp. 140-141]