Now, as to what you saw the second time, it is a dream pertaining to the same thing. It is an indication of its firmness, because the word of God shall be done, and it shall be completed swiftly
Other versions
King James Version
And for that the dream was doubled unto Pharaoh twice; it is because the thing is established by God, and God will shortly bring it to pass. English Standard Version
And the doubling of Pharaoh's dream means that the thing is fixed by God, and God will shortly bring it about.New International Version
The reason the dream was given to Pharaoh in two forms is that the matter has been firmly decided by God, and God will do it soon.