#1
In other words, have you ever written a riff that you later found out already existed? I do it all the time and it pisses me off. Most of the time, they're riffs that I already know subconsciously but since I can't pinpoint where I heard them from, I think they're mine. There's noting worse than writing a good riff and then finding out months later that someone else already came up with it; the only reasonable thing to do from there is to just scrap it and move on. Other times, I'll come up with a riff that's similar in structure to another song. Recently I've been trying to dabble into writing metal songs (I'm more of a classic rock player) and I made a riff that was really heavy but I realized 5 minutes later that it was the same structure as the main riff from Megadeth's Holy Wars. I get so paranoid when I come up with a new material because if it sounds really good to me, then I automatically assume that I probably heard it somewhere and forgot about it. I don't want to start making songs with those riffs because if they are from another band, then I'd be labeled as a plagiarist. Any thoughts?
#2
I've had this happen many times. The only options are: scrap it or try to alter it in some way. Usually after I alter it it actually sounds better to me than the original. I don't think you have to worry about plagiarism, there're tons of riffs that are similar in many famous songs. Off the top of my head, Keep Away (Godsmack) = Hey Man Nice Shot (Filter), Comedown (Bush, the bassline) = Shot Through The Heart (Bon Jovi).

There's nothing wrong with having a similar sounding riff to another song, just as long as it doesn't sound like you're rewriting the song.
#3
I reckon this happens with about half the riffs I write - possibly more.

I've thought a few times about starting a "Have I Stolen This Riff?" thread on here for people to post their ideas and get comments on if it's too similar to something else.
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#4
^ Thats a great idea because this happens to me all the time as well
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#6
Please use Musician Talk or other appropriate forums for this type of discussion. Songwriting & Lyrics is for written (poetry, lyrics, prose, stories, etc.) original work.