In a recent article, G. Malle and G. Navarro conjectured that the p-blocks of a finite group all of whose height 0 characters have the same degree are exactly the nilpotent blocks defined by M. Broué and L. Puig. In this paper, we check that this conjecture holds for spin blocks of the covering group 2.An of the alternating group An, thereby solving a case excluded from the study of quasi-simple groups by Malle and Navarro.