In all our considerations concerning B-trees, we assumed that the keys are unique. However, this does not have to be the case because multiple occurrences of the same key in a B-tree do not violate...

In all our considerations concerning B-trees, we assumed that the keys are unique. However, this does not have to be the case because multiple occurrences of the same key in a B-tree do not violate the B-tree property. If these keys refer to different objects in the data file (e.g., if the key is a name, and many people can have the same name), how would you implement such data file references?