The good news is that it seems that, when using the function Lightmap pack on multiple objects, Blender does create a new UV map for each object yeepee!
The bad news is that you can’t swap from one map to the other in the UV editor when editing multiple objects:
If I click on UVMap.001, the UV editor will display the UV map UVMap.001 of the active object while all the other objects will still be displaying their UV map UVMap.
Another bad news is that the user can’t add manually a new UV map to multiple objects
Except from that, UV editing on multiple objects work pretty well !