Two cameras, one with normal rendering and one with replaced materials?

Hi, I need to render the same scene to two cameras. One normal rendering, and for the other one, I want to replace all materials in the scene (or world) with a shader-based unlit material during rendering. Is there a easy way to do this in UE4?

Seems this can be done by convert all materials into dynamic material instance, but since I’m using one same material for all objects, is there a simplier and portable way? By portable, I mean normal maps should work without this special modification.

Thanks.