Joseph Vines - Two sons named William

I'm running into the same thing. My gg grandfalther is Joseph Vines. My g grandfather is William Vines. The only Joseph I can find death records is in Alabama. My gg grandmother is Hannah, buried in Montana with William. I don't think he had 2 families, children being born the same years. It doesn't make since. I think there are 2 Joseph Vines and the record have gotten twined together. They may even be related.