Normal Pass is generated from Face's Normal Vector
When you bake the normal map, you are converting the XYZ component of each surface's point normal vector into the correspective RGB color (according to the type of calculation: object, tangent..).
Is something that is not related with textures or shading, just geometry.
The result is correct, every point of your surface has a normal pointing out (local Z axis). That's where the blueish color is coming from (XYZ=>RGB).
What you probably are trying to bake is the Color of the Normal Map. Maybe you have combined several maps or some of them are a procedural textures converted with the bump node... what you need is to bake the Emission Pass (one of the fastes to bake you'll need just 1 sample, as with SSS Color, Glossy Color, Diffuse Color...) of an Emission shader with Strenght=1 that has the color you want in imput:
Here's an example of baking the Normal from procedural textures: