The Collaborative International Dictionary of English v.0.48:
Dualist \Du"al*ist\, n. [Cf. F. dualiste.] 1. One who believes in dualism; a ditheist. [1913 Webster] 2. One who administers two offices. -- Fuller. [1913 Webster]WordNet (r) 3.0 (2006):
dualist n 1: an adherent of dualism