Musical works and composers will frequently have more than one name. The Magic Flute is an excellent example. In German text, its name is spelled Die Zauberflöte. Transliterated, it loses the umlaut over the "o." Translated, we say The Magic Flute.
How does this affect your searches? It means that when you search for The Magic Flute within the online catalogue, you may not receive listings for Die Zauberflöte. In order to find all the resources that could be helpful to you, you need a uniform title.
There are a few ways to go about this: