G&S: The Gondoliers (1984)

Marco and Giuseppe Palmieri, the most favored of all the gondoliers, choose Gianetta and Tessa to be their brides. While celebrating their marriages, Marco and Giuseppe are informed that one of them is really the King of Barataria - but it is not known which. Gianetta and Tessa are delighted with the idea of one of them being Queen. However, all are cast into despair when it is revealed that the King was married (in babyhood) to somebody else!