12. The system of claim 8 , wherein the means for comparing first and second hash values is executed in response to the results of the means for comparing first and second lengths and respective first and second temporal features of respective first and second documents.
12. The system of claim 8 , wherein the means for comparing first and second hash values is executed in response to the results of the means for comparing first and second lengths and respective first and second temporal features of respective first and second documents. 13. The method of claim 12 , wherein the duplicate-determination means is executed in response to a query adapted for automatic future execution and in response to an automatic execution of the query.