There are no dual purpose goats, like you can find in the cattle world. However you can run easily a dairy goat enterprise and mate your dairy (British saanens, Toggenburgs or even better Anglo Nubian) nannies to Boer (meat) billies. You would then use ALL (male and female) offpsring for meat, and milk your nannies. Every so often - if you want to increase your number of breeding females - you would mate one or two to a really good dairy male (that's so that you get the milk quantities, Boers and Boer crosses will not have decent enough amounts of milk to run some kind of dairy enterprise).