According to the manual, the Reset button does not affect data.
Resetting the My Book Live Duo Device
If you have set a password or a static IP address on the My Book Live Duo dashboard and
have forgotten it, pressing the reset button while the device is powered up resets the
password to the default value of none and to default IP settings. Resetting does not erase
your files.
However, it should be remembered that the Factory Restore in the Dashboard will ERASE ALL DATA!
Quick Factory Restore formats the drive. Full Factory Restore secure erases the drive.