Although disallowing duplicate search keys in the ADT dictionary is reasonable for some applications, it is just as reasonable to have an application that will allow duplicates.
a. What are the implications of inserting identical items with the same search keys? What are the implications for the removal and retrieval operations?
b. What are the implications of inserting items that are not identical but have the same search key? Specifically, what would the implementations of add, remove, and get Item do?