I had never heard that there are any sorts of doublets and contradictions in the flood story. In her lecture on Doublets and Contradictions, Christine Hays talks about some of these things. She talks about how it is said that the amount of time where rain was present isn’t consistent. Some passages say 40 days and others say 150. It seems strange to me that I would not have known about or noticed this before.
She also says there is a lot of repetition and contradiction in the Bible whether they are in the same passage or not. Some parts of books are basically repeated again in another book later on. There are two creation stories in Genesis 1 and Genesis 2. It seems as though the image of God is different in Genesis 1 and 2 as well. This leads us to believe there could be different authors and a lot of revisions. Growing up, I never learned about these kinds of propositions and ideas. I had never been introduced real studies of the bible and what religious scholars actually were saying about the text that was a big part of my life.