The popular traditional jazz number Silver Bell, with music composed in 1910 by Percy Weinrich, has two themes, the first comprising 16 bars in the key of F. The melody 'bounces down the ladder', you may recall. Then it modulates into the key of Bb, for a Chorus which also comprises 16 bars.
There is also a popular spiritual called Sometimes My Burden is Too Hard to Bear, played by many jazz bands. I have heard people wonder whether the music for this spiritual was 'lifted' from the Chorus of Silver Bell.
Well, the original Weinrich sheet music proves that they are indeed exactly the same tune.
So I think we should credit the composer of Sometimes My Burden as Percy Weinrich and not as 'Anon' or 'Trad'. According to one source, the words for Sometimes My Burden were added in the 1940s by someone called Eugene Williams.