Some distributors modify WD20EARS (Caviar Green) and sell them as WD2003FYYS (Enterprise Model) or Caviar Black.
They copy the sn and pcba number from genuine disks (as the packages are transparent) and duplicate labels, so the online product registration is not reliable.
They also use modifying software to change information in disks and even the firmware version, so the disk-info software is not reliable as well.
Introduction of the software:
http://we.pcinlife.com/thread-1497504-1-1.html
This guy encounter a fake WD2003FYYS
How to change LBA, etc.
http://blog.xlysoft.net/post/95.html
Even if customers test the speed and cast doubts, the seller will say it is a reasonable variation in performance between products – WD doesn’t give a minimum performance guarantee, isn’t it.
Then is there a reliable method to judge if a drive is genuine or not? (e.g. an apparent difference in PCB ) If not, then could there be any in the future?