I get the same issue in write mode when I add dynamics to part 2, it adds it to part 1.
I found the issue out copying and pasting note from Piccolo to Flute 1, and for some reason Flute 1 has a different set of dynamics, as I was adding dynamics to Flute 1, it would add them to the Piccolo, as well.
I have not tested to see if it happens with changing notes, but my thought is no. The clarinet 1 part that I copied to clarinet 2, had a wrong note that I entered incorrectly. I had to adjust both parts.
Robby