That looks like machine doubling and not a true DD. I am far from an expert however. http://www.coinbidders.com/Strike Doubling Flyer - PDF.pdf
Here is the VAM World list of all of the 84-O's. http://www.vamworld.com/1884-O+VAMs Go to work and use all of the PUP's to see if those on this coin match up with one of them. Chris