The double entries problem isn't just with LEGO, either. Video games are absolutely plagued with that garbage and it's not uncommon to see 5-6 listings for the same game. To make it worse, a fair amount of products I send in will come up as the fake/bad listings even when I scan the UPC. I've seen listings that Amazon themselves sell on that get pushed behind fake listings with some homemade picture and a bad description.
It has really gone downhill in the past 2-3 years or so. Between all the Renewed listings popping up, people making bad listings to get around approvals/restrictions, and Amazon seemingly losing control of their own ability to check in shipments (went six years without a single lost item, then suddenly Amazon loses $8k in LEGO across four consecutive shipments so far this year and refuses to reimburse, claiming they received 40-50 pound oversize boxes that had nothing but really, really heavy air in them).
And even as a buyer things have become a pain in the ass because of all the sellers with counterfeit/used-as-new/etc products. Same as above, I've been shopping on Amazon for almost 15 years and never once had to return an item for being expired or used or whatever. So far this year I've had to return 7 different things (some expired food, a half-used tub of pomade, and even some bootleg sticks of RAM). The worst part is that a few of those came from very large sellers; the kind with tens of thousands of reviews but barely above a 90% rating. It's frustrating knowing that if I dropped that low or sold expired food or whatever my account would be closed immediately, but these other sellers get special treatment because of their sales volume.
Sorry for the rant. I usually don't post much on here but this topic has really hit home lately. Also the Seller Central app search is absolutely terrible lately as well. You can search for something very specific like "lego #####" and get no results (or a completely irrelevant/bad result) for a product with a 1,000 sales rank, but the same search pulls it up just fine in the Amazon shopping app.