I have one red light, one green light and two white lights that I display at night while underway. I also have one all-round white light that I display while anchored at night. I don't need anymore than that, I'm pretty sure.
I also have dome lights, flashlights, spotlights, lanterns, etc for other uses.
So, I would say if your boat has only one light, it's either really small, or you got gypped.