A request (in Italian) has been made on the Neapolitan Wikipedia (nap.wikipedia.org) to change the name of the language "nap" from "Nnapulitano" to "Napulitano".
The reasoning is (basically) as follows:
The doubling of the letter "n" at the beginning of the word is the effect of the neuter article "'o"
Since there is no article before the word, the consonant should not be doubled
You should of course read the request for more details. The user claims to be a native speaker of the Neapolitan language.