I tried to implement a multiple Shadow Lights system with Ashley's advices from these two topics :
When I set the Shadow Light opacity to less than 100, you can see that the Shadow Light cast multiple polygons from a Tilemap object with Shadow Caster behavior, that overlap and so cumulate alpha (surely to avoid having a big concave polygon). This make a multiple lights system (with Alpha threshold as Ashley mentionned) impossible. I made a little project to illustrate the problem : https://www.dropbox.com/s/2d5gmgwxes129ua/MultipeLightsShadows.capx?dl=0 Just mouse click to apply or remove alpha threshold.
I manage to get close to the desired result by setting each Shadow Light at 100% opacity on a dedicated layer with 50% opacity, to get the "wrong" shadow into a flatten one. The superposition of the two layers give a good result but then I don't kwow how to apply a alpha threshold effect on the sum of the two layers. Here is the second example :
Any idea ? I find no soluton.