If you’re baking with the “Blender Render” engine, Blender will bake to whatever image you’ve assigned to the object’s UV’s. So if you successfully baked C_colour then you’d need to assign your desired S_colour texture to the objects UV’s for baking. Otherwise it will overwrite the C_colour texture.
If you’re baking with Cycles, Blender bakes to whatever image texture node is selected in the Node Editor (material mode).
