The phrase "a different libretto" is correct and usable in written English.
It can be used when referring to an alternative version of a libretto, which is the text of an opera or other long vocal work.
Example: "The director decided to use a different libretto for the production to give it a fresh perspective."
Alternatives: "an alternative libretto" or "another libretto".
"Paavo Haavikko wrote a radio play in the early 1960's," Mr. Sallinen said, "and then made two different librettos out of it.
Then, in 1997, San Francisco Opera asked me to write a libretto.
Each with a libretto by a different author, they were premiered over a seven-year period (1830-1837) in different Italian theaters, with different singers as the royal protagonists: Giuditta Pasta ("Anna Bolena, Maria Malibran Maria Stuardaanda") and Giuseppina Ronzi de Begnis (Elizabeth I in "Roberto Devereux").
The 1896 libretto also offers a different ending, in which Tosca does not die but instead goes mad.
Italian composer Luciano Berio wrote a sequence of pieces meant to accompany the work, with a projected text to explain how things came out; novelist Italo Calvino wrote a libretto that incorporated all the extant music in a different context.
The prettiest-looking of the three books is CRYSTAL FLOWERS: POEMS AND A LIBRETTO (Bookthug, $18), by Florine Stettheimer, also edited, though for a different press, by Ms. Gammel and Ms. Zelazo.
The poems slowly coalesced into a jigsaw of a libretto.
The S3 barks an entertaining libretto, a cross between a larger six and a flat-four.
Not only did this original score, notated for orchestration, have different passages (and that different ending), it was accompanied by a detailed libretto by Prokofiev and the dramatist Sergei Radlov that diverged in important ways from Shakespeare's play.
Writing a libretto demands techniques different from those for writing spoken drama.
