As I bake new prefab the old lightmaps gets deleted even they are moved in separate folder

[mayurBhagat]

Hi, I have game levels as prefab which I need to bake. I baked one prefab(JapanGate) and move generated lightmap to new folder(JapanGateLightmap) after baking prefab. Now if I generate lightmap for second prefab in the same scene old moved lightmap also gets deleted. Do we need to generate lightmap for different prefab in different scene? Do we need to add all scene in build used for lightmap generation ? If it it is so how it can be helpful ?