OP Polonius3 1,009 | 12,458 10 Jan 2015 #61I originally thought the Polish name Duplaga might have been the Polonised form of some French surname like Duplage, De La plage, Deplage. The retreating Napoleonic troops occasionally had their wounds nursed in Poland and sometimes settled there. However, now I am inclined to believe that the name was originally Polish and traveled to France with émigŕes, refugees, DPs, etc. After all, the -ga ending usually with a pejorative connotation does appear in Polish (e.g. łomaga, ciemięga, etc.) and that could have been the case with Duplaga as well. The only locality incorporating "Duplaga" is Duplagan in the Philippines -- not a very likely source of a Polish surname.As far as further pursuing this thread on French soil perhaps the following link may be helpful:archivesnationales.culture.gouv.fr/chan/chan/onomastique.htmlThat is the onomastics centre of the French National Archives. Dunno how responsive they'll be but good luck anyway!