Tell me if you see anything, I'm still trying to figure out this DD, I really want to find one!!!! But don't we all..
Hard to see anything from pictures - only possible cause of any doubling is Machine Doubling - considered a mint production error and not worth very much!
I have found machine doubling on all letters of coins at some point in time, especially on Jefferson Nickels.
Send Atrox001 a PM, he might send / post a few close up pictures of what to look for on the 1971-D Kennedy half dollar Doubled Die Obverses. Larry has always been willing to help me out with questions. Good luck with your hunt.