Flickr member, Seam_73, gives us this great comparison shot of various heads seen on clones and Mandalorians alike. You can note that the heads that come with set 7913, Clone Trooper Battle Pack, are all typical flesh clone variants. The Mando heads from set 7914, however, are quite different and a little...creepy.
The best I can figure is that these are modeled after Death Watch commander Pre Vizsla (see reference). I really don't see why one of the four identical Mandolorians couldn't have had a black lightsaber and cape. Instant Vizsla and variety!
(Via Seam_73's Flickr stream)