Unfortunately RailClone doesn't create a unique array for each spline if they are overlapped when using Extend X/Y size to area mode. When they overlap, RailClone expects to uses splines one inside the other as alternating include-exclude areas.
This explains why you get unusual results with partially overlapped splines:
In this case, I'd recommend using Forest Pack to place the lights. To do this:
- Convert your splines to a surface by applying a UVW modifier. If necessary open the objects properties and turn off Renderable
- Apply a planar UVW Map modifier to the surface
- Create a Forest object. Add the Light as a scatter item and add the floor plates object as a surface/
- Set the Mode to UV from the Surface rollout
- In the Distribution rollout, set the map to Full and adjust the X and Y unit values to get the correct spacing.
- If necessary, to placement on individual ceilings you can add am Unwrap UVW modifier to the surface and adjust individual UV islands
I've attached a file demonstrating this technique.
I hope that helps, please let me know if you have further questions.