I’m guessing by “peek-through” you are saying the reverse of the flag was cut away to show the Corps Badge or center device. I believe thats rare and a timely process, not including a waste of material. According to the Quartermaster General's drawing the badge was to be sewn on both sides. Thats HQ, Division & Brigade flags. Some field made flags may be deferent.

Does that help?

Happy Trails!
Tom Martin
www.Confederate-flags.org
www.Piedmontflag.com