In The Beatles' song Ob-La-Di Ob-La-Da, the last two verses are essentially the same except Desmond and Molly Jones switch actions. I've included a line by line comparison below with the differences emphasized.
Line by line comparison
Happy ever after in the market place
Happy ever after in the market placeDesmond lets the children lend a hand
Molly lets the children lend a handMolly stays at home and does her pretty face
Desmond stays at home and does his pretty faceAnd in the evening she's a singer with the band
And in the evening she's a singer with the band
What is the reason for this switch? Was it a flub by Paul?