You could do this. I’d probably just have one note and at the top I’d indicate that I have both hard and soft.
I use Bear, which would look like this. But how you do this isn’t really important as long as you understand what you mean.
In fact when I think about it, two notes is not recommended. The problem is that you find one note, read it, and it says that you have soft copies. But you forget to look for other notes, and so you don’t see the one where you told yourself you have hard copies, and now you’re confused.
One note keeps it simple.
No. A single ID relates to the files, wherever they are, in whatever format.