I am pretty sure somewhere on the forum you can find information how many levels we need to add to multiple cover characters to sell them for extra ISO (totally made up example: lvl 2 cover 2* till lvl24 to sell for 750 ISO rather than selling each cover for 250). Unfortunately the search is not allowing me to find it. Any ideas or links?
With 3* it’s irrelevant now for me as I have them all on the way to championing (and then it’s better to add a level). But for 4* i don’t have iso to champ it could work. I wonder if it works for 2* as well as I don’t have a full farm yet (any idea?).
Back when there was an increased buyback in two-star Magneto after they changed his Purple you could earn some HP buy getting two colors of the same colors, leveling it to max and Selling the dupe. There probably is some sort of increase of the price there, but I don’t know if it’s enough to be ISO positive.