Now why the two dreams that were virtually the same? Do you remember, a little bit later in the story, that the baker and the butler each had dreams that were very similar in their construction? And then two years later, the Pharaoh also had two dreams that were very similar in construction, and that they, too, came one right after the other. Well we find out the answer in Genesis 41 where Joseph (now the interpreter of dreams) says:
Now when Joseph had his dreams, I am sure that he did not understand a great deal. But quite a number of years had gone by—thirteen, to be exact—and time, experience, maturity, and revelation had taught him a great deal. The doubling of dreams was God's way of emphasizing. He was emphasizing that the process leading to the dreams' fulfillment was going to be occurring very quickly. So Joseph is saying that the matter is already settled in God's mind, and nothing we can do can turn it aside. So we had better get humping, post haste—right away.