A discussion at The Corner deals with movie remakes, both good and bad. What about operas that turned out much better the second time around?
Iphigenia en Tauride: Niccolo Jommelli (1771) vs. Christoph Gluck (1779)
The Flying Dutchman: Pierre-Louis Dietsch (1842) vs. Richard Wagner (1843)
Manon Lescaut: Daniel Auber (1856) vs. Giacomo Puccini (1893)
Ariadne auf Naxos: Georg Benda (1775) vs. Richard Strauss (1912)
Faust: Louis Spohr (1816) vs. Charles Gounod (1859)
The Barber of Seville: Giovanni Paisiello (1782) vs. Giacchino Rossini (1816)
Alceste: Georg Frederic Handel (1750) vs. Christoph Gluck (1767)
Falstaff: Antonio Salieri (1799) vs. Giuseppe Verdi (1893)
Romeo and Juliet: Vincenzo Bellini (1830, as I Capuleti ed i Montecchi) vs. Charles Gounod (1867)
Fidelio: Pierre Gaveaux (1798, as Leonore) vs. Ludwig van Beethoven (1805)