You want to do one listing with different sports cards so that the buyer can choose which one they want? That's called a variation listing and is supposed to be for when you have the same item but with different options such as color, size etc. I know that there are listings with various sports cards but eBay may take them down if they don't follow their variation policy.
In the top half of the listing form there is a section called 'create variations' and that's where you would set up the different variations. You may need to switch to the business listing form to see the variation option.
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