Amazon may have had no knowledge of the cheaper product.
China is COMMUNIST and believe, among other things, that intellectual material is property of the collective, not the owner, inventor, whatever. Knockoff has been a tactic to increase market share forever. Noticed it first while in SE Asia, early 1970's. Watches, vinyl albums, and such were the bit suspect items. $9 Rolex? $0.50 Stones album? At first glance, they looked and felt legitimate.
Given the deluge of US/Euro products the greedy placed into China over the decades, small wonder. One company or another IS faking most everything, sometimes in the same factory that makes the legitimate brand name. Soooo.....knockoffs are a grand temptation for lyingcheatingstealers to buy from Chinese sources, complete with OEM looking marking, labels and packaging and sell for a grand profit to the unsuspecting western customer.
Chinese companies ARE capable of making world class goods. Their unscrupulous cousins are quite capable of faking an orgasm for you.
Just, 'Buyer, Be Ware'.