Thanks for the quick response Peckris. What may appear to be a D or an R at the beginning of the reverse legend on the first coin is merely a line making up part of the central design motif. The legend reads: A /Greek letter sigma/I. Then: K/A/W. Hopefully this might help nailing it down to a particular time frame/mint. Funnily enough; my wife, who is a professional classicist, can't make much sense of this legend.