You asked "And looking at the matched set of pistols you sold, SN 176...I can't help but think these were actually a couple of the very earliest JC Reilly's. Pistol SN's for Reilly are problematic but...these look appropriate. Did both pistols have the same SN?"

Yes, both pistols were marked 176; that seems odd to me, but perhaps that was customary with pairs of "duelers".