As Champagne raises awareness and popularity we see it mixed with other dilute genes, Champagne with Dun is a very common combination within the rare Champagne combinations that is. With both colours being dominant only one of each gene needs to be present to express the colour.
Champagne with Dun Phenotype
You will see Dun factors, though usually lightened, as well as traits from Champagne: mottled skin and eye colours including blue, green, hazel, amber and light brown.
Champagne with Dun Colours
Here is the list of Champagne and Dun combinations; once again many names are given to the same genetic coat. I am still using my assumed/made up name for the wild bay combinations until there becomes a more official one.