indeed the word duplex it show up alot around here in usa. not only electral related items but other stuff also like duplex pump ( two pump in one unit) etc etc .. same with singleplex sometime i called uneplex ( short term french for single unit) but the other hand about grounding pin for both singleplex et duplex it been hot debate in few forum not only one here but few other electrican forums too have simuar debates and we end up with one answer just use the common sense the code dont say anything about grounding pin is up or down. mainly depend on the plugins itself that all but can debate more later

merci marc

Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)