Technique determine (or detect) duplicated data. The techniques involve: in response to determining that data at a first position in input data is the same as predetermined data, determining a feature value of a selected portion of input data; determining whether the feature value matches with a pre-stored duplicated data pattern in a duplicated data pattern list; and in response to determining that the feature value matches with the duplicated data pattern, determining an association of the input data with reference data which is associated with the matched pattern.