1. A computer-implemented method for deduplicating an incoming data sequence, the method comprising the steps of: storing signature values for a plurality of data blocklets of a parent data sequence in a deduplication index; sequentially storing signature values for at least some of the plurality of data blocklets of the parent data sequence in a first storage location outside of the deduplication index; determining that a first data blocklet in the incoming data sequence is absent from the parent data sequence; storing a signature value for the first data blocklet in a second storage location outside of the deduplication index; determining that a second data blocklet that follows the first data blocklet in the incoming data sequence is present in the parent data sequence, the second data blocklet having a signature value that is stored in the first storage location; and copying at least a portion of the contents of the second storage location into a cache to expedite access during deduplication of the incoming data sequence.