There should be a word for That Moment when you realise

[Herbert Augustus Chapman]

that the version of the song you always knew was in fact a cover.

Just heard 'Denise' by Randy and the Rainbows. After forty-odd years of thinking that Blondie had written it. Though it does explain why they never wrote a tune as good as that one.

Nearest feeling to that recently was hearing the Beach Boys version of that surf track on Pulp Fiction.

All along the Watchtower being Dylan not Hendrix is always good for winning a bet too.