But do they commingle inventory? That's the real problem with Amazon, not that fakes are listed on the marketplace, but that you can't even trust Amazon as the seller.
According to a quick google search Walmart does not commingle inventory. However, I think they will eventually once their tech can support it. Target started commingling inventory so it is only a matter of time before Walmart does. From a logistics standpoint it makes 2-day shipping much easier since you can spread inventory out across the country.