Auxiliary verbs in San Dionicio Ocotepec Zapotec, an Otomanguean language spoken in Oaxaca, are associated with two constituent structure representations: one monoclausal and the other biclausal. The Zapotec auxiliaries show syntactic similarities to causatives in German, Spanish, and French, as well as the Urdu instructive/permissive, where constituency tests also give evidence for two c-structures. Using Optimality-Theoretic LFG, this paper argues that these cases involve predicates with a single f-structure representation where two c-structures emerge as equally optimal under the relevant constraint evaluation. These structures exist in parallel to each other, recalling Goodall's (1987) more general approach to parallel structures in syntax.