It seems like it's not a Nardi after all. In Brunori and Curami's book it's written: "At the Mille Miglia, with number 647 was the team Bornigia-Pacini on Alfa Romeo 2500 with a bodywork quite similar to Gurgo Salice's berlinetta (that was by Nardi, ndr). This bodywork was made by Motto as well. These elements created a lot of confusion and some researchers have erroneously thought this was a twin Nardi Alfa Romeo, but it was committed by Bornigia, owner of a big Alfa Romeo dealer in Rome"