How did My Passport replacement register as "Legacy Product"?

I purchased a 2TB My Passport mid-February and two months later it began disconnecting itself nonstop. Support was contacted the end of April, but they could not have been more useless if they tried. In a matter of days I could no longer access the backup volume for my Mac and lost data I can never get back. So I transferred everything I could, ironically to my ten year old external hard drive which the My Passport was intended to replace.

Long story short, I was promised a brand new drive exactly the same as what I purchased, and it finally delivered a few days ago. The drive, as well as the packaging, look identical to what I had purchased and by all appearances looks brand new. HOWEVER, when I registered the drive, the serial number returned very different information than that of the original.

When I registered my original drive, I received the following email…
WD Product Registration 01|386x500

But when I registered the replacement drive, I received the following email instead…
WD Product Registration 02|386x500

This makes no sense to me, but has me absolutely livid!

Can someone explain how this even makes sense?