To answer the questions: I do want both lights to illuminate my object, I just don't wish to see the highlights from both.

Eric, thank you! I have Shader Plus, and I never looked at the Lighting Control before (how stupid of me!). I have a question about it thougth:

There is a known issue with Carrara, and that is that when you are using proper GI (light Sky light) and you have a Sky Dome (and actual model of it) in the scene, even when your Sky Dome is set NOT to cast shadows, the GI will not penetrate it, and will be obscured by it completely.

Is there a way to counter this problem with the Lighting control somehow? I notice it has GI settings, although I don't exactly understand what that means. Or maybe it can be done with some other plug-in from your shop?