Well, AW says they were both signed in person, that would explain the messiness of the first one. They do not provide any details though
I can't really give an opinion on the first one. It does, and some letters especially, do have, a certain feel which is close to other James Stewart signatures, but I couldn't say. The second one does look authentic in my opinion.
The Far Country is right. One of the Mann Westerns. Not a classic, but a pretty good film. James Stewart plays a very indifferent, stubborn guy in that one. As for the autograph, the "James" looks pretty good, I think. And the t's in Stewart. But I don't know. Some autographs shout authentic, this one doesn't shout, to me at least.