Indeed, Sir

it was pretty common, up until radios became household appliances, for a performer "covering" someone else's song to make up their own lyrics or additional verses, which may explain why you're having difficulty finding a "complete" set of lyrics. For example, "Oh By Jingo" (which you may recall from an episode of Jeeves & Wooster), a popular song originally from a Broadway musical called "Linger Longer Letty" which ran in the winter of 1919-1920, has a ton of verses and variations.