No, it would not be a sport, although the tendency to rebloom is genetic. It probably just means that you have outstanding gardening skills and that you are providing perfect conditions for the iris. Quite a few irises that are not listed as reblooming varieties bloom a second time in Southern California because the conditions here are so salubrious.

It's also possible you got a different iris, since historic irises are pass-a-long plants and can get mixed up. There are a number of reblooming lavendar blue historic irises that look similar to yours. Do you have a photo? It would be nice to see it in your lovely garden.

Renee

Thank you for your reply. I sadly do not have a picture of it. I tend to lean to the mixed up/mislabed explanation - since I live in Northern Europe - and this iris seems to bloom in late May and again in October - some years the late flowers didn't develop since it was too cold ...our winters are cold - nothing like SoCal growing conditions .-)