An older cousin once gave us an example of a twice-told mondegreen.

In an old country song there is a line that says 'My heart is withered like the petals of a rose I saw dying today.'

My cousin evidently thought it said My heart is withered like a fiddle, etc.

Later she forgot that line and evidently couldn't remember which musical instrument it referred to and in front of my older sisters sang, 'My heart is withered like a banjo of a rose I saw dying today.

True story.