OK, I know little about this kind of thing, just looking for input. A quick internet search didn't turn up anything for this date. It's slabbed F12 by PCGS. Pretty much all the letters in United States of America show some degree of doubling, and the MM.
Need some experts in here. Is this even a known variety? As if the 1912-S wasn't good enough, if this is a DDR this is some honking coin.
Machine doubling, not Longacre doubling. I don't believe I have ever seen Longacre doubling on coins designed after Longacre died, or on coins that he designed where the hubs were modified after he died. For example Longacre doubling is common on indian head cents, but it disappears on the obv after the modified the obv in 1886 (Longacre died it 1879), but the reverse was not modified and Longacre doubling can still be found on the reverse through the end of the series.
and i always thought it can be seen into early 1900's, goes to prove your never too old to learn something new...