Different serial numbers for the same person?

Soldiers who have two Army serial numbers are often soldiers who had served as both enlisted man and officer.  At least in the WW2-era, enlisted men had a distinct series of serial numbers; officers had a different series of numbers.  Officer's numbers often started with and 'O' (not a zero), followed by a sequence of numbers. 

For instance, my grandfather was drafted in November 1941, as a enlisted man, and was assigned Army serial number 37129311.  He was later commissioned and promoted to officer status and assigned a new Army serial number beginning with an 'O' : O-1306027.

It is also theoretically possible that the soldier served in two different branches of service, such as the Marines and the Army, or the Army and the Navy. 

Dear Mr. Schweitzer,

Thank you for reaching out on History Hub. There are several reasons that one person could have been assigned multiple service/serial numbers. As Mr. Deiss indicated, the most common is that they went from enlisted service to officer service. Officers were assigned separate service numbers, often they are a lower number. Other reasons can include reenlistment under a different name or name change (this happens more commonly with women than men) or enlistment in a different branch of service.

We hope this helps to answer your question. If you believe that you may have received incorrect information from a record center, please reach out to their customer service. The National Personnel Record Center in St. Louis for military personnel records’ customer service line is 314-801-0800. Thank you!

Best,

Cara Moore

National Archives in St. Louis