Lightmap and Realtime shadows: Different colored shadows

I have a scene in which i bake a lightmap. Ambient light and one directional light are set. The baked shadows achieve pleasing results. The objects that cast dynamic shadows onto lightmapped objects, however, cast a shadow that is darker than the lightmapped shadows and darker than realtime shadows on a non-lightmapped object. The tint of these shadows is also different.

Does anyone have an idea why this could be happening? Could it be that the default shaders using beast lightmapping ignore ambient light when calculating the light values in a shadowed region?

thanks!