@clive
I thought the conceit of a one-hit wonder wasn't about how many songs appeared on a Billboard chart but rather how ubiquitous one song was, only for the artist to be barely heard from ever again
Terry Jacks' _Seasons in the Sun_ is my goto example
My first thought on two-hit wonders using his definition is Warren Zevon (not on the list, but technically should be). But can you really be a two-hit wonder if you have a Greatest Hits album?