just the 36 has it. the 3 is doubled under the top, the center point to the west, and very slightly to the east side of the 3, and the 6 is doubled to the east and west at and inside the top. MD, right?
If you are talking about the small doubling you see on the back top of the 3, then I believe it is machine doubling or strike doubling. I can somewhat see a step/shelf coming off the top of the 3,as I said, however I don't see anything pointing towards a Double Die.
found more MD on the reverse. almost looks like it was re-engraved or something. the last 5 letters of AMERICA look almost like a different font altogether.
I think it could just be die deterioration. The dies for the buffalos didn't stay in pristine condition for long, so can be seen on the "melting" late die stage strikes.