Various embodiments for differentiating between data and stubs pointing to a parent copy of deduplicated data are provided. Undeduplicated data is stored with a first cyclic redundancy check (CRC) seed. A stub pointing to the parent copy of the deduplicated data is stored with a second CRC seed. Subsequent to reading the deduplicated data, the first CRC seed is associated with the undeduplicated data, and the second CRC seed is associated with the stub. A CRC check is performed using one of the first and second CRC seeds. If the CRC check is positive, an I/O operation is allowed to proceed. If the CRC check is negative, an additional CRC check is performed using another one of the first and second CRC seeds.