Yeah, I won't pretend to have a ton of knowledge about the subject at hand, but as best as I can tell, 12 is the cap, so to perform 3 naval attacks in a row would put you at 0, and they had 2 approximately an hour later.
2 attacks at 12:02, and 1 at 12:04. My guess is they started with 10 MAP, the first attack "doubled" so to speak because of the server lag, using only 4 MAP and then they did the 3rd, which used another 4, bringing them to 2.