There are so many "double ear" Lincoln's spread over the years, I don't even bother to look for them, so couldn't tell you what you have.
Hey, first post in this community! What a coincidence, I found my first 2006 DDO-004 on Tuesday as well! Anyone have an idea about the population of this variety compared to other double ears? I have only been searching for a few months and early on decided I wanted to start a double ear collection and this was the first one I found.