Take a look at Parshas Noach, go to Gen. 6:17 and read. It goes like this:
"17 I am going to bring floodwaters on the earth to destroy all life under the heavens, every creature that has the breath of life in it. Everything on earth will perish. 18 But I will establish my covenant with you, and you will enter the ark-you and your sons and your wife and your sons' wives with you. 19 You are to bring into the ark two of all living creatures, male and female, to keep them alive with you. 20 Two of every kind of bird, of every kind of animal and of every kind of creature that moves along the ground will come to you to be kept alive. 21 You are to take every kind of food that is to be eaten and store it away as food for you and for them." 22 Noah did everything just as God (Elohim) commanded him. "
Then check out the very next set of verses in chapter 7:
"1 The LORD (Hashem) then said to Noah, "Go into the ark, you and your whole family, because I have found you righteous in this generation. 2 Take with you seven of every kind of clean animal, a male and its mate, and two of every kind of unclean animal, a male and its mate, 3 and also seven of the birds of the heavens, male and female, to keep their various kinds alive throughout the earth. 4 Seven days from now I will send rain on the earth for forty days and forty nights, and I will wipe from the face of the earth every living creature I have made." 5 And Noah did all that the LORD (Hashem) commanded him."
Let's compare. First God says to take two of ALL types of animals. No exceptions. Then a few seconds later Noah is supposed to take, not two, but seven (some would say seven pairs and I also think that makes more sense) of clean animals. First "two of every kind of bird" then "seven of the birds of the heavens." What's with the change of directions?
Given the repetitive nature of these two paragraphs, it seems that Noah was given two directions and indeed the directions are not the same. Go to the Documentary Hypothesis, the first paragraph was written by E, as you can see that Elohim is doing the directing, the second is written by J and as you can see Hashem is doing the directing. It certainly seems likely that we have two traditions of the same story being melded here.