A processing method for duplicated data includes the following steps. A query request is received from a client, in which the query request includes a requested fingerprint value. A hash tank corresponding to the requested fingerprint value in a memory is searched for the requested fingerprint value. When the requested fingerprint value does not exist in the hash tank corresponding to the requested fingerprint value, the following steps are executed. An addition table in the memory is searched for the requested fingerprint value; and when the requested fingerprint value exists in the addition table, an invalid duplicate message is sent to the client.