It simply has no 'protection' against flashing the same firmware over and over; no real reason why it should have such a protection. It may only check whether it's the right brand or firmware type for that drive.
If you don't want to lose data, you should invest in a backup instead. For example a couple internal Samsung F4s and then use an external samsung f4 (or multiple) as backup. With current HDD prices so low, your data must not be very important if you only store it on one HDD. Think about your HDD on two or three HDDs, separate and independent of eachother. That's protection for your data!
So perhaps you would want to buy at least another F4. They make excellent backup disks, especially since the bigger ECC should mean less problems with bad sectors.