yes and yes - probably (above and OP)

All pop music has these similarities - it is a feature of "wot wurks, wot sells", and don't forget the song "Mr Woo's a Window Cleaner Now"
Is that cashing-in on an old success or what?

cf Neil Sedaka in his Calendar Girl day.

In the book "How to be a Succesful Songwriter" the one common bit of advice from many well-known and respected pop composers (inc Sedaka) was to: "Take a song, write new lyrics, then write a new tune to that"

I think the word is "derivative" but in the throw-away mental wallpaper that is "popular consumption", derivative is easy money all too often.