A method of determining whether a data segment is a duplicate using cooperating deduplicators is disclosed. The data segment is received. A first deduplicator is operated to to determine whether the incoming data segment is a duplicate based on first information available to the first deduplicator regarding stored data segments that are stored in a memory. A second deduplicator is selectively operated to determine whether the incoming data segment is a duplicate based on second information available to the second deduplicator; wherein the selective operation of the second deduplicator depends on the determination made by the first deduplicator.