As Tom Lehrer once memorably intoned - "Plagiarise, even if people all evade your eyes.... But please .... call it research!"

There are only so many words, and only twelve notes to play with.

CF "Something in the way she moves" by James Taylor and "Something" by George Harrison inter alia.

Every honest songwriter gets the same feeling from time to time, and Paul Simon and Bob Dylan must have felt it often in their early days!