The first edition of FitzGeralds Rubaiyat was published in 1859. He published three other versions during his lifetime. A fifth version was published after he died based on notes found among his papers.
As far as I can tell this is a unique situation. I personally dont know of any poem that exists in five different authorized versions. Some of the differences are significant; some are minor.
The version I perform is slightly different from any previous edition. I selected these 96 verses from the five authorized versions, with a view to presenting a version that lent itself best to being heard rather than being read on the page. That version is available here as a PDF.