In this comment we refute recent claims (Aleshkin et al 2003 Semicond. Sci. Technol. 18 L35) that experimental observations of the shot noise with Fano factors below 1/2 in resonant double barriers are a signature of coherent versus sequential tunneling. We point to the principal theoretical flaw in the analysis of this work and to the contradiction of this claim with our own earlier work and that of the wider literature on shot noise in small electrical conductors.