There are 10 reasons why the duplication would fail:I、Devices issues:1. Using an ultra-slim /non-standard USB.2. Unstable quality of the Flash device.3. Bad quality of the USB extension cable.4. Bad quality of the MSD/SD adapter.5. The SD card is locked.6. Bad source.II、Capacity issues:7. The data location in the source exceeds the capacity of the target (under "Only Data Area" copy mode).8. Huge differences of capacities between the source and targets.9. The capacity of the target is smaller than the source (under "Only Data Area" copy mode and NTF/Linux format).