It turned out pretty much the way we figured it would.
Commingling ten distributors sets of Energizer batteries makes sense, but not as much sense as just buying direct from Energizer. They don’t lack the volume.
Even on Amazon, it’s not uncommon to find several new listings for an item fulfilled by Amazon from different sellers (including Amazon). That’s beneficial for Amazon because they don’t need to own all of the inventory and the sellers get a listing with good reputation to leverage if Amazon goes out of stock. In the perfect scenario everyone wins - Amazon makes money, the seller makes money, and the product is still available to the customer. You get all that without commingling, but with it, you also save physical storage volume.
I see the point you are trying to make, but Energizer batteries are a bad exemplar for it. Even if all of the batteries are the exact same SKU, some of them may be 10 years old and some of them may be fresh from the factory. I've had this happen with several (perishable) products from Amazon.
(I suspect but have not proven that Walmart actually rotates UPCs/SKUs on identical product so they can remainder it out).
also, you're probably aware of all the made-up brands which sell like, thousands of versions of staples like HDMI cables on Amazon... all of that exists because FBA made it possible for people to start random business in consumer goods, basically by (my understanding) using Alibaba to find manufacturers and FBA to find customers and connecting the two. It's all exhausting now because the fake brands have crowded out the real ones, but for a long time that was what the economy becoming more efficient looked like (at least in one sense... maybe not the sort of efficiency that actually benefits the customer, though, since in practice a lot of the gains were found by capitalizing on Amazon's reputation to sell cheap stuff for more than it was worth).