Well, it might be true that Duros were actually the predecessors of Neimoidians; they never had a soft corner for Neimoidians. Duros were the colonizers of the planet of Neimoidia, and centuries of breeding and evolution led to the formation of the specie we call Neimoidians. However, these Neimoidians lacked many traits that were found in a Duros; instead, their “qualities” were mostly quite the opposite of what Duros possessed. So, for sharing their looks yet lacking their values and attributes, Duros hated Neimoidian’s guts.