The Girl of the Golden West is a direct steal. I've seen two productions at City Opera, and the motif is right there for all to hear. It may even be the same key.
I have always thought Un Bel Di was used as a definite idea (to coin a phrase)for Love Is a Many Splendored Thing, the Oscar- winning song from the 50s.
Of course, if you write a solid melody and then hit the audience over the head with it, it will sound like Puccini. A bus-and-truck Puccini maybe, but still Puccini.
Come To Me, Bend To Me is used in Phantom as an homage to Alan Jay Lerner who was the original bookwriter/lyricist and died before real work began. The Lerner-Loewe estates knew this.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher