So after reviewing so many German brand chocolates, I still can't read German. I only learned to enjoy it. I know the word "Duo", means "Two", which is very fitting for this particular chocolate.
By the look of it, it is a combination of white and milk chocolate. If you like dark chocolate, then sorry, this one may not be for you. I love milk chocolate, and the combination with white chocolate just made sense. The chocolate followed closely with Ritter Sport tradition with its silky fine texture, and the rich milky chocolatey flavor as it melts in my mouth. The milk chocolate really overpowered the entire chocolate, and the white chocolate simply added the creamy, vanilla sweetness to the milk chocolate. I got the illusion that I was eating an extra milky chocolate, and it was worth every bite.
I give it a 8.5 out of 10.