When I come up with something particularly good, I take a screenshot of the melody + chord symbols and send it to a couple of my musician friends to ask if they recognize it as anything.

One time, they identified an idea as the bridge to an old pop song, but otherwise I’ve thankfully been in the clear.

I simply don’t think about it. If Chino Moreno can get away with using the chorus chord progression of “Hit Me Baby” in one of his songs and the most that happens is laughter about it in the comment section, it’s not an issue.

Alternatively, there is nothing new under the sun. Music has seven fundamental notes that can only be arranged so many different ways and still sound pleasing to the ear. It’s an inevitability that somewhere, you’re going to use the same chord progressions as thousands if not hundreds of thousands of other composers, you’re gonna write the same licks, you’re gonna play the same riffs. The difference is in atmosphere, genre, and performance. Don’t stress it too much.

Everything is derivative of something else. Thag made that drumbeat on a rock 20000 years ago and it has passed down in oral history to eventually be in a Nirvana song.

This sometimes results in songs like Dani California that are almost certainly overt or unintentional copies of another song. When you find out your song is subjectively too close to another song you do the right thing, whatever that may be between you and the original musician.

I’ve done this. Yes, they did exist. That’s one of the risks of creating songs from melodies stuck in your head

Nope, happens a lot to me, too. Worst part is that whatever you’re accidentally plagiarizing, will immediately sound great and will be really easy to write, because of course, you’ve listened to it before. And it can be nigh impossible to distinguish between accidental plagiarism and just being in a flow.