John Wexler still lists it as a DMM. Coppercoins still lists it. Variety Vista delisted it.
The two that Wexler delisted were the 1951 D/S and 1980 D/S.
That said, there could be three alleged 1956 D and S varieties. Wexler shows two, the one here with the purported S between and 1 and 9 and a second with the purported S immediately east and slightly north of the D. I have had some discussions with two other collectors who think there may be a third possible D and S, with what appears to be an S immediately SE of the curl of the 5.
The only one that makes me pause is the second, listed as 1956-D 1¢ WOMM-001, with the possible S NE of the D. I think the two varieties wide NW (here) and wide NE )speculated) are far too strange for mm placement. The stronger explanation would seem to be die damage.
JMHO.