It depends. If it's something like Series 1 and Series 2 being issued over two years, that should be one listing because it's one set, two of the main sports just happen to have a season that takes place in two years.
If it's something like an insert that is issued over multiple years, then the cards should be listed with the year they were released with. For example, the early Upper Deck Heroes insert in several sports were issued with consecutive numbers across multiple years, and those are listed with the year they were released with.
For promos that are issued over a series of years but are for one set, I generally put them together as one but it is really something that needs to be determined on a case by case basis. I can't remember which set it was, but I know at least one non-sports set had promos issued the year before it was actually released, and they are listed as a promo for the set and notated that they were issued the year before.
Hope that helps.
VERY slow trading due to health problems. Not transferrable so safe to trade with, just moving is painful and can't always access the cards.
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