I use here a flat white wall with three spot lights facing to it. Each light has a different color: red, green and blue. Light spots are overlapping.
Image obtained in MuPAD using point lights.
The same model in JavaView with default JavaView parameters.
The same model again but I changed the angle for the spot light to check what colors I will get on the intersection of two different lights. I suppose that I should get colors similar to those below.