This paper offers an argument to analyse the Spanish form /a/ as a syncretic case marker for accusative differential object marking (dom) and dative. The literature on free relative clauses has established that syncretism allows the repair of feature mismatches arising from contradictory selectional requirements between the matrix and the embedded predicates. By combining clitic left dislocation constructions (CLLD) and free relatives, it is shown here that dom and dative grant the same repairing effect in Spanish, so it follows that they must be syncretic categories. The same type of configuration distinguishes the directional preposition a and the dative case marker, which is taken to indicate that these elements are mere homophones in the language. Furthermore, an analysis of the repairing effect of syncretism is offered.