Yes, normally the long-finned ones are specially-bred for that trait, but it is likely that your short-finned ones (should you get those) will have a few long-finned offspring, as it is a trait found within the normal ZD gene pool!
Thats what I figured, I asked because I was looking at fish at a store and the long finned were labeled max size 2-inc but the regular zebra were labeled 6inc.
I though zebras grew only to 2, I guess the store made a typo and were thinking of giant danios