When you log in on a hunter... the Aspects can have up to 2 stacked. I logged in with my Aspect of the Dragonhawk on and I was able to put Aspect of the Viper on and have both effects work. Should be looked into :)

EDIT: Looked into it more. I tried Aspect of the Dragonhawk and Aspect of the Monkey on and both of them gave me dodge chance allowing me to have 54% dodge chance.