If you have a saltwater license for RI, CT or NH then you don't need to buy a MA one.
and if you live in one of those states make sure you buy it in your home state....if I'm not mistaken Reciprocity is only good if License is purchased in state that you reside in...if you buy it in another state it will only be good in that state that you purchased it in.
"If you're arguing with an idiot, make sure he isn't doing the same thing."