I don't get where your trying to go here Lina. You ask if cards in a sport set are the same, and for me to say they all are is untrue. Every set will have certain cards worth much more. However, the bulk of the set of maybe 400-500 cards(95% of it) will be known as common cards, all of them worth a set price. Usually this is only .5-.25 depending on the set.
When I meant a choice listing, ecspecially with cards, I meant that we could make A LISTING for that set and year, and then be able to list INDIVIDUAL card #'s that the person can choose from (maybe in check box form) and select just like as if they were selecting a quantity. I've seen listings before (and they aren't in violation of Ebay's policies) that say you can have your choice of 10 out of these say 31 or 40 listed numbers. It works, but it's a HUGE pain in the butt when after one person has bought it, and now you have to re-edit and re-list the remaining card #'s. To be honest, I think it's just a way for Ebay to pad their listing fees a little to be honest since it does make you re-list that very item again and again until you have sold them all, instead of just making one simple listing that would do the same and if the listing fee was slightly higher, I don't know about anyone else, but it would be fine with me!
Now since you did mention "Multiple Item Listings",I hadn't heard about that before. I should look into it, as maybe they will end up doing exactly that, but I got a feeling that all they do is list the EXACT same item, just with a quantity number attached to it. No choice of what card # or such you might want to choose.
I know that this is just using cards as an example, but I'm willing to bet that there are alot of sellers out there that may find themselves in the very same both with other items that might end up being the same way.