Jumping on two add I've now had 2 experiences of buying counterfeit drives on Amazon from different sellers. I've probably ordered only 4 hard drives off of Amazon ever, so that's a 50% counterfeit rate.
Both sellers issued refunds without trouble because I bought them under Prime. One seller seemed genuinely surprised they had a counterfeit in stock.
Both of these counterfeit drives look very, very convincingly authentic, except the serial numbers don't match real ones and don't validate as real ones with the OEM.
The first time, I actually argued with Seagate over it being real, until they pointed out that aside from the serial number not being in their databases, it's not even in the correct format for any of their drives.
If you care about your drives and you're buying on Amazon, only buy under Prime. And when they're delivered, check the serial numbers with the OEM first thing (usually via warranty validation). Don't buy anything not on Prime.