There's a clear change in pavement color in both Bing and Esri World just under this pin. Combined with open MoDOT data indicating the southern terminus for DD lies at Lake Bluff Drive, I'm convinced State Route DD terminates here.

But it also seems that Stone County continues a "DD" designation as part of its county network all the way to Coney Island. This would not be part of the state supplemental route network. There is precedent for this phenomenon with State Route CC in Jefferson County (way/18526984): North of US 67, we have County Road CC; south, we have State Route CC.

I think we should change the ref tag south of this note to "CR DD" and mayhap even consider a route relation with network=US:MO:Stone.