using multiple uv sets

I’m creating buildings in Maya that are built in a modular fashion. The textures I make for these have to be pretty clean (bricks in particular) or else the tiling will be obvious. These buildings are old and weathered, so adding a second uv set to add large areas of dirt, grunge, and general weathering would be ideal. My concern is how Unity will only accept 2 uv sets from Maya, and the lightmap is generally used for one of the 2 sets. Does this mean if I use the second uv set for a diffuse texture that I have no options for a lightmap? Any suggestions are greatly appreciated. Thanks.

Just make two different materials and map them to different vertices. Then add different materials in unity under the mesh render component.