Laughing, it's been a few months since eBay stopped people selling multiple lots - business sellers can still show "more than 10 available" (for example) but for ordinary sellers, you now have to list each item separately.
It's not as bad as it sounds, as you can list one item, then when it's listed, press the "Sell one like this" option and just keep doing that until you have listed all your duplicate items.
Where I've listed multiples, I've put an item in the listing saying "I'm selling several of these on separate actions and am willing to combine postage if more than one item is bought by the same buyer" (that is, if you expect people to want to buy more than one).