:I haven't looked it up in a dictionary, so I don't know what the difference is supposed to be between a principle and a property -). But I do believe that the people who call it the "superposition principle" are talking about exactly the same thing as the people who call it the "superposition property". Anyway, Google says that the phrase "superposition principle" is 20 times as common as the phrase "superposition property". I'd say Wikipedia should stick with the overwhelmingly more-common term, whether or not it's linguistically and pedagogically ideal. But maybe I'm misunderstanding what you're proposing. 

 :Anyway, since "superposition property" appears to be a synonym for "superposition principle" (less common but not unheard-of), it seems to me that it's perfectly sensible to create a redirect page from there to here. -)