That sounds like the old way they had of making copies prior to Xerox machines.
My birth certificate is like that. Totally black background and white letters.
After WWII, it was common for soldiers to take their DD214s to the courthouse and have them recorded for convenience. They would look like that.
When I ETS’d, they told us to record our DD214’s at the county so we could always get a real copy in case we lost ours.