Catalyzes the stereospecific reduction of the C-4 keto group of dTDP-4-dehydro-6-deoxy-D-allose, leading to dTDP-6-deoxy-D-allose, an intermediate in the biosynthesis of the mycinose moiety of the chalcomycin antibiotic. dTDP-6-deoxy-alpha-D-allose + NAD(+) = dTDP-4-dehydro-6-deoxy-alpha-D-allose + H(+) + NADH dTDP-6-deoxy-alpha-D-allose + NADP(+) = dTDP-4-dehydro-6-deoxy-alpha-D-allose + H(+) + NADPH Belongs to the NAD(P)-dependent epimerase/dehydratase family.