Maria
For most of us penguins it would not be advisable to do two hard runs in a row. If the 5k is just to participate and finish, and you are used to runing two days in a row, have at it.
If on the other hand, 9 miles is near your longest distance, and or the 5k is an actual "race" to you, I would err on the "take a day off" side, and start a new week doing your 9 mile next weekend.
Just a note, I am great for advising others to take it easy, and not so good at it myself and have the scars to prove it!
Good running. Let us know how the 5k goes.
Jack