This coat is a great example of how costumes can look different under varying conditions. The coat does not look the same at first glance, but there are a few clues. The button placement and overall cut of the garment are the same, though the buttons seem to have been replaced. Lastly, Shannon Hale, the author of Austenland states on her website that they are indeed one in the same:
"Later, I find out the costume coat and hat JJ Feild is wearing are the same ones Colin Firth wore in Pride & Prejudice. Somehow, I've managed to enter Austenland. It's ridiculous. And it's so much fun."