One Dream or Two?
Pharaoh had Egypts most talented dram necromancers. What caused him to ignore their interpretations (following Rashi's comment whereby their interpretations were unsatsifactory) and accept without reservation the message of a Hebrew slave?
A close reading of the text can help us solve this problem.
It appears that there was a disagreement between Pharaoh and his advisers over whether he had had one or two dreams. Whilst Pharaoh may have woken up after the first dream, he only recognizes that he had dreamt after the second dream. Indeed it is only after the second dream that he realizes that he had dreamed a dream (Bershit 41:7). Notice how Pharaoh's experience is described in the singular.
Notice also that when Pharaoh relates his vision to Yoseph he twice uses the singular. "In my dream, behold, I was standing on the bank of the Nile...Then I saw in my dream, and behold, seven ears of grain were growing on one stalk" (ibid 17-22). Pharaoh believes that he has had on dream.
So when Pharaoo tells his wise men of the dream he uses the singular. " Pharaoh related to them his dream..." yet they respond in the plural, "but no one interpreted them for Pharaoh" (ibid 8). His necromancers insisted that he had had two dreams, whilst Pharaoh knew that he had had only one. So Pharaoh rejects their advice.
Pharaoh however, is intrigued with the tale of the chief cupbearer. In relating his experience to him, the cupbearer, he points out that according to Yoseph both his and the baker's dream were one.
Indeed the first words that Yoseph says to Pharaoh are: "Pharaoh's dream is one"(ibid 24). Yoseph goes onto explain why that one dream was repeated: "Concerning the repetition of the dream to Pharaoh twice that is because the matter is ready [to emanate] from God, and God is hastening to execute it" (ibid 32).
In light of this we can understand why Pharaoh accepts Yoseph's explanation of the dream and rejects those of his own wise men.