Forum:Is capitalisation enough to distinguish two articles?

I've just come across two articles I've never seen before and am curious what you guys think about the distinction between them: I've now put up disambig notes at the top of each article, but I wonder if that's enough of a distinction. Should it actually be Dark Planet (novel) and dark planet remaining at the planet? Or is the capital letter "P" enough to distinguish the two? I've never seen two articles on this wiki separated by just capitalisation, so we might want to include this case in the naming conventions section of the manual of style, once we decide how we want to handle it.
 * Dark Planet is a novel
 * dark planet is a type of planet