There are restrictions on listing the same item in multiple listings. See https://www.ebay.com/help/policies/listing-policies/duplicate-listings-policy?id=4255&st=3&pos=2&que... Among these are that only 1 auction listing without a bid will display in search results. We are seeing only 3 listings in your list of active listings, none of them duplicates. We'd need the item numbers of the ones you think both show the same bid to see what the issue is (e.g. bidder bid on both through confusion or because s/he wants both).
Multiple item listings are for fixed-price listings only. eBay used to have multiple item ("Dutch") auction listings but they were very confusing for both sellers and bidders and they did away with them many years ago. You can have one auction for a "lot" of 2 or more of the same item, or different items, as long as you are clear what the winner gets for the final auction price (one single price buys all, it is not a per piece price). Or you can set up a single fixed price listing (Buy It Now with or without Best Offer) where the buyer chooses the quantity s/he wants at a per piece price.
