A processing method for duplicated data includes the following steps. A stored file is partitioned into a plurality of raw tanks and a plurality of meta tanks, in which the raw tanks correspond to the meta tanks in a one to one manner, and each meta tank has a stored fingerprint value of the corresponding raw tank. A duplicated data determination request is received, in which the duplicated data determination request includes a requested fingerprint value. At least one of the meta tanks is read, and the requested fingerprint value is compared with the stored fingerprint value of the read meta tank. A referred counter value of the read meta tank is modified, and the modified meta tank is stored back, when the requested fingerprint value is the same as the stored fingerprint value of the read meta tank.