Basically, yes. Though, they were probably not doing it physically together because Kim Jong-un was much too young for building his own political career when his father was still alive. What it really says is that they both have had a hand in developing and promoting political concepts like self-reliance, the "military first" policy and other ideas like that in their country. They may have done all that at different times in the history of their country, but they're absolutely coequal in bringing them about. In other words, he and his father could equally be called the originators of all those ideas that have become part and parcel of what is now the official political ideology of North Korea.
This house is mine as much as yours.
This sentence means that the house belongs to me as well as to you. We're both absolutely equal in owing this house. And there is not much else that can be said about this expression because it's really a very basic phrase in English.