Usually these no's are the abbreviated service no. (letter-first letter of surname, number- last four digits of service no.) Looks like the G? version was done in error. the other no. I'm unsure about maybe done at the factory?
René is correct, here’s a contemporary WWII US Army poster to the proper marking your clothing and equipment from here "Marking of Equipment" poster - WWII - EPHEMERA & PHOTOGRAPHS - U.S. Militaria Forum Your friend may be able to get the clothing identified here A "Laundry Mark" Search Database is now available. - INDIVIDUAL AND UNIT RESEARCH - U.S. Militaria Forum