If they understood football minimally, they would generate players like DMC-MC, not DC-DMC.. I don't know anyone good at being centre back and defensive midfielder at the same time.
Depends on the team. Some teams like to have 2 big guys at the back that really cant play other positions. Other teams like Borussia Dortmund like to have dangerous players everywhere. It depends on the type of team, but known players like Javi Martinez of Bayern and Mat Hummels and Sven Bender can play both. Although DMC,MC is the more frequent type