Hello younger bro,
As you said, there are two hard drives in each server. It is possible that the hard drives are configured in RAID 1 mode which will reflect as single drive to the operating system.
You can reconfirm it from the iLO GUI under storage tab. If it is confirmed as RAID 1 configuration, then the backup i.e. both the hard drives have same data written.
In case if you still have doubts, please share the images from iLO GUI showing the storage information or raise a support ticket with HPE and we would help you.
Regards,
KK