Ah, I see what you mean. I'd say that they are probably equal in terms of google web searches with maybe an edge for the ensemble, primarily because their recordings show up all over the place, but the cantata is far more notable in terms of the history of opera in Germany and even lent its name to a book L'Arpa Festante:Die Münchner Oper 1651-1825. I guess it's a question of primary meaning, and I don't really have an answer. Maybe using a qualifier for the ensemble would be the best way to go. I can make a separate article for the cantata and then they can both be resolved with hatnotes.