I'm attempting to replicate this locally.
I've created a new admin user using the default 'Admin' account.
When I go to edit this account after creation, I'm presented with New Password and Confirm password. I am not prompted for the old password.
Now when I sign into the newly created admin user, then navigate to Settings -> Administrator Settings, I'm asked to input the old password (for the newly created admin account) then the new password, and confirmation. Please note that this is ONLY encountered when editing the admin as the non-default admin account. You should not be able to change any of the administrator accounts while signed into the non-default admin.
Could you please provide me with the steps you had taken to reproduce this issue ?
Technical Support Supervisor