There are a couple of things you can do but i don’t think you’ll like them…
First, you can try switching to Blender, Max or Maya.
Second, You can export your model twice with each UV channel in each export. Then import them to another modeling software and copy/paste the lightmap UV’s.
Third, you can try using a single channel with no overlapping UV’s and set your textures according to this UV layout of course.
Fourth, You can generate unique UV’s inside the editor, but it gives messy results most of the time.
Fifth, you can go fully dynamic lighting.