I was recently going through the Western "Rifle and Pistol Ammunition Hand Book from 1931 and discovered that under table titled “European Automatic Pistols” which gave both the European caliber designation and the “American Caliber” The 7.65mm Borchardt was shown as the “30 Cal. Borchardt” and the 7.63mm Militaire (Mauser - Militaire) is shown as the “30 Cal. Mauser”.
The listing of cartirdges in this book only lists the 30 Mauser.
This seems pretty late to differentiate between the two cartridges since on one page in the Draft 1902 DWM catalog the 403A1 is shown as the Mauser and the “A1” is crossed out so the designation of the Borchardt as the 403 and the Mauser as the 403A must have been dropped about this time.