The Kitty Wells song intentionally copies the Hank Thompson melody in order to tell the same story from the woman’s perspective. I don’t know whether Thompson’s copying of the Carter Family song is intentional or not. It’s also worth noting that A.P. Carter’s copyright does not imply that he actually wrote the song. In the early days of commercial recording, the first to register a song owned the copyright, and many Carter songs had been around in oral tradition long before the family began performing them.

A couple of other notable examples of melody-sharing: The Western classics “Red River Valley” and “Can I Sleep in Your Arms Tonight Lady” share a melody. Hank Williams copied his own melody in “Move It on Over” and “Mind Your Own Business,” and this melody finds its way into the Bill Haley and the Comets standard “Rock Around the Clock.”