The data looks repetitive but is not really rendant. 

In this special case, the lookup keys are the same as the relation name. In fact, any relation that is not flattened has the same characteristic. But, it's a design decision not to rely on the relation name to infer the lookup keys.

If we don't store the lookup keys and another step (say flattening) changes the name of the relation, we cannot correctly infer the lookup keys.