The technique introduced here includes a system and method for identifying and mapping duplicate data objects referenced by data objects. The technique illustratively utilizes a hierarchical tree of fingerprints for each data object to compare the data objects and identify duplicate data blocks referenced by the data objects. A progressive comparison of the hierarchical trees starts from a top layer of the hierarchical trees and proceeds toward a base layer. Between the compared data objects (i.e., the compared hierarchical trees), the technique maps matching fingerprints only at the top-most layer of the hierarchical trees at which the fingerprints match. Lower layer matching fingerprints are neither compared nor mapped. Data blocks corresponding to the matching fingerprints are then deleted. Such an identification and mapping technique substantially reduces the amount of mapping metadata stored in data objects that have been subject to deduplication.