Single Side poly rendering and Light map usage question

Hey guys if I have a mesh, and on the static mesh lightmass settings if I flag it to use two sided lighting will that allocate extra space on the lightmap atlas for the backface? Basically I don’t want to pay for the backfaces light map usage, if that makes any sense. I cant seem to find an answer on the web. Thanks

Dave

It does not add any extra lightmaps.