[jweber.ged]
Otto, the Illustrious, b. c836, d. 30 Nov 912, Duke of Saxony; m. Hedwig, d. 24 Dec 903. ('Charlemagne & His World (Heer), p. 226, shows Otto's wife as dau. (illeg.) of Arnulf, King of Germany, Emperor c863-99, & Oda of Bavaria; Arnulf was son of Carolman, King of Bavaria (c828-80) & Litwinde; Carloman was son of Louis II "the German", King of the East Franks (c805-76) and Emma of Bavaria. Louis was son of Louis I "the Fair". See Brandenburg for Arnulf's ancestry, however, Brandenburg shows no such daughter for Arnulf. Isenburg shows Hedwig as daughter of Henri, Comte de la Marche. Moriarty says Hedwig d. 24 Dec 903, does not identify parents.).
Otto may NOT have married both wives, as they appear to be two different alternative wives with different ancestry. But I followed the Hadwig von Babenberg line from Bernd Josef Jansen, World Connect db=bernd-jansen, so I am making her the 1st wife, and Hedwig of Germany as the 2nd wife.
Note: Peter Stewart, in criticizing the accuracy of Stuart's 'Royal for Commoners' points out that RFC names him Otto of Erlauchten (as if it is a place), whereas his name is Otto I "der Erlauchte" (German for "Illustrious").