I am going to go out on a limb and say that this is a very clever fake.
They used the Hartman auto as part of the dupe, I mean, if Hartman signed it, then the Nirvana stuff must be real, right? Wrong.
I actually think the Hartman is fake too, but forged fairly well.
I think the Nirvana stuff is also bad.
But I could be totally wrong.
If it is bad, this just goes to show the lengths people will go to, to sell bogus Nirvana autos.