Rawlings designated an "X" following its model number for pro stock gloves in the 1940s and 1950s. That's a single "X". I've seen the double XXs on other brands following numbers or letters but am not sure what these represented. "X" I was told by Rollie Lattina at Rawlings also meant "experimental".
So which brand do you have and do you have an image of your glove?
I have that same model glove and have sold 2 of the same over the past 5 years. They are nice, well made gloves. Someone I talked to said they might have been made for the military. No idea if that is true.