[dwd]

Totally inevitable.

I was listening to a recent album and the opening/closing riff of one of the songs was identical to something I used to play in my room between studying 30 years ago.

I remember my own discovery process. I had been playing the acoustic part of "Welcome Home - Sanitarium" with it's two finger chords and was messing around with similar chords higher up the neck and found a few that sounded really cool. Did I copy that song? No, but definitely inspired, the other guys probably discovered the riff in a similar way - just noodling around until they heard something they liked.