At most the contrast has been adjusted. I have seen B. nasicornis in person that were very similar in color.

Rhino Viper/B. nasicornis
http://en.wikipedia.org/wiki/Rhino_viper

Gaboon Viper/B. gabonica
http://en.wikipedia.org/wiki/Gaboon_viper

Both are very beautiful species, but Rhinos have my heart.