If my memory serves me the mintmarks were not added to the dies for quarters in 1990. If that is the case that would mean there is no way it could be a D/D. Probably strike doubling but impossible to say for sure from that small photo.
Like I said on your other thread with the same question - - - I don't think mintmarks wre added to quarter dies in 1990 so there would be no way it could be a D/D. Probably strike doubling but impossible to say from the small photo.
Resize on D mint mark zoomed as much as I could on the D. I did reference this on looking up the 1990 D Quarter http://coinoftheday.blogspot.com/2007/10/1990-d-quarter-dollar.html Doubled the size but can't get any higher without losing detail majorly.