1. Aberdeen white and victoria white are allels of different loci. That's why they are expressing two different shades.
2. The pure-breding progeny wild-type progeny in the F2 are the result of "recessive epistasis". Both gene pairs exhibit complete dominance, but a recessive homozygote of either gene pair is epistatic to the other gene (supresses its expression). Actually this is a type of duplicate recessive inheritance pattern, in which the progeney are produced in 9: 7 ratio.
3. The F2 ratio is approximately 9: 7 (181/ 139).
4. The F2 ratio results from complementary gene action. The presence of any homozygous recessive allele is epstatic to the other gene. The genotypes aaBB, AAbb, aabB, Aabb produce the same phenotypes.