Turn off isoline display. I wrote a little script that replaces export/export selected. It just turns off isoline and then exports. simple but a life saver.
Why do you need to do that? It should be possible to make a script to save the lightmap(s) after baking and then reassign them after baking the other set.
In 3d studio max go to Script > listener or hit F11 then select all objects and in the white field delete everything and type : deleteModifier $ 1 and hit Enter.
Yeah, but script is easier/faster. Select all the meshes, go to the Utility panel, click the More... button, choose UVW Remove and click OK, then click Materials.