"Don't not respect your mother" is a double negative. "Don't disrespect your mother" isn't really a double negative, and is no different from saying "Don't disobey the law", "I don't dislike pineapples", "Don't disregard the rules", etc. It means the same technically as the positive way would, but because it is said in the negative (with not and dis-), the tone implies more of an argument than "Obey the law", "I like pineapples", "Regard the rules", etc.