DJU, I can speak to the ones I own. Hungary and Italy were part of the Axis. To briefly summarize, Beretta made the Model1934 in 9mm corto (Although I understand there were some made in 7.65mm called the M1935). When Italy wanted to surrender to the Allies, the Nazi's took over the Beretta factory and over saw the production M1935s for the Wermacht. These were 7.65mm.
In the case of Femaru, a Hungarian manufacturer that later evolved into FEG, a 9mm kurtz model 1937 was in production for the military, police and civilian market. Under contract the Nazi's had Femaru produce a similar model 37, with the only changes being only in 7.65mm and an added thumb safety. The Germans seemed to prefer the 7.65mm caliber in these two instances.
So unlike the Walther PPK that I understand started life in 7.65mm and then 9mm kurtz was added later, the Beretta and Femaru models mentioned above were 9mm shorts initially and 7.65mm models came later.
I love these 7.65mm and 9mm short guns. They are a hoot to shoot, especially with the reduced cost of ammo that I handload.