nope sorry, looks like the part of the 9 scratched off and that extra metal was deposited near the end. That's why it looks the way it does.
I cant tell you for sure what it is, could it be a die chip? Possibility though in my mind there is absolutely no doubling. You can see at one point in that coin's life that it was struck by someting and left an indentation (sp?) right by where that excess metal is. Maybe someone can explain what it is better than I can. Just in case you arent aware there are no known 1956 DD(or at least what I have been seeing, I will try to review a little more cent sites to verify). Here is an example of a 55 DDO http://www.lincolncentresource.com/doubledies/1955ddo.html
Its pretty plain to see that a small part of the 9 is missing and is fixed to the outer edge of the 9. How did it happen though is the question...
I'm wondering if it couldn't be an RPD. In Billy Crawford's book on Lincoln Die Varieties, he does have a listing for a 1956D in which the "5" was repunched with a partially rotated "5" beneath it. The same thing could have happened here. It's too bad Billy isn't around. Chris