Can't really tell from those pics, but it may be DDO-3 http://www.lincolncentresource.com/doubledies/1972ddo3.html
Based on the clockwise direction of the doubling, I am thinking it is either 1DO-003 or 1DO-008 on coppercoins.com. Check for markers, and great find!
i think i have found 12-15. 13 different varieties i believe. my best find was the 002. it always is nice to find a ddo