22 shadow casting lights with Don in P5 SR4 using Firefly.

Whether Poser recognizes a light as an infinite light or a spotlight doesn't seem to depend on the Internal Name of the light, but rather a parameter called lightType. The lightType value does change as you convert a light from spot to infinite using the gui. The name doesn't change probably because it's internal (not visible to the user via the gui) and it didn't used to matter what the name was to the renderer. Now in SR4 it matters! Not whether it's a spot or infinite light, but whether it renders depth map shadows.