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Sam Smith won four Grammy Awards last night. And that was good news for Tom Petty. Petty and another songwriter will get royalties from Smith's hit "Stay With Me" because it sounds a lot like one of their songs. NPR's Elizabeth Blair reports.

ELIZABETH BLAIR, BYLINE: First a little background - when Tom Petty's people heard this...

(SOUNDBITE OF SONG, "STAY WITH ME")

SAM SMITH: (Singing) Oh, won't you stay with me 'cause you're all I need.

BLAIR: They thought that sounds a lot like this...

(SOUNDBITE OF SONG, "I WON'T BACK DOWN")

TOM PETTY: (Singing) Well, I know what's right. I got just one life.

BLAIR: Tom Petty's "I Won't Back Down" from 1989 is strikingly similar to Sam Smith's "Stay With Me." So Petty's people called Sam Smith's people, and in no time, Petty and his co-writer, Jeff Lynne, got songwriting credits. Sam Smith said it was pure coincidence. And Tom Petty said these things can happen but they did want credit and royalties. Michael Harrington teaches music business at the SAE Institute in Nashville.

MICHAEL HARRINGTON: A friend played this for me, and he just said, I want you to hear something. And it came to the chorus and I said, whoa, that's Tom Petty.

BLAIR: Harrington says this isn't the first case like this.

HARRINGTON: The most famous case is George Harrison "My Sweet Lord" being that it infringed The Chiffons "He's So Fine."

BLAIR: One music fan on YouTube went ahead and mixed the two songs together.

(SOUNDBITE OF YOUTUBE VIDEO, "MY SWEET LORD VS. HE'S SO FINE")

BLAIR: George Harrison was found guilty of plagiarizing subconsciously, but still had to pay songwriter Ronnie Mack's publisher nearly $1.6 million. But Mack got nothing. He died years earlier.

Heather Phares of allmusic.com thinks Tom Petty's claim to the Sam Smith song is a bit of a stretch.

HEATHER PHARES: It's just a very standard song progression.

BLAIR: Phares says a more egregious example is Robin Thicke's 2012 song "Blurred Lines."

(SOUNDBITE OF SONG, "BLURRED LINES")

ROBIN THICKE: (Singing) And that's why I'm gon' take a good girl. I know you want it.

BLAIR: Which sounds a lot take Marvin Gaye's 1977 "Got To Give It Up."

(SOUNDBITE OF SONG, "GOT TO GIVE IT UP")

MARVIN GAYE: (Singing) But my body yearned to be free.

BLAIR: The ruling's still out on that one. A copyright trial begins tomorrow. Elizabeth Blair, NPR News. Transcript provided by NPR, Copyright NPR.