Because of the relatively small amount of notes in the scales of Western music and because of the rules of tonal music, it happens that similar tunes appear in very different contexts. Here are some of my favourite musical coincidences.
Mozart / Peña Baiona
A few years ago I found a funny musical coincidence between the Peña Baiona / Griechischer Wein and the Introitus of Mozart’s Requiem, which has a whole fugue on the same theme:
Amélie Poulain / Lord of the Rings
I always have a thought for these poor Ents in the Lord of the Rings whenever I watch Amélie Poulain:
Superman / Tino Rossi
Here is another (brief) similarity between one of John Williams’ great themes and one of Tino Rossi’s famous songs.
Ponyo / Wagner
This one is not a coincidence, I like how Joe Hisaishi adapted Wagner’s Ride of the Valkyries for Ponyo.