In a functioning factory vehicle, these numbers always match. The failure usually indicates one of two scenarios:

If the vehicle was previously tuned using different software, the internal checksum calculations may be disabled or modified. The VCM Suite will flag this as a validation failure.

The MPVI2 and MPVI3 use specific USB data transfer standards. A frayed cable, a loose OBD-II connection, or a failing Bluetooth connection (for MPVI3 wireless) can drop single bytes of data. A single bit flip is enough to fail a 32-bit checksum validation.

Your heart sinks. The vehicle may not start. The stock file may be corrupted. Or worse, the ECU might be bricked.