How to edit BSP UVs

I noticed when I created a static mesh out of a BSP object it assigns two UVs, why 2 coordinates?
Is there a way to edit or reapply these UVs?

One is for textures and the other one is for the lightmap. After you convert brush to a static mesh, you cannot edit UVs inside UE4. However, you can export the mesh, edit it in your content creation software and import it back.