New England Asters tend to be fairly short lived. But, they reseed well enough that, especially in informal plantings, it's easily possible to not notice that the original plant is gone and has been replaced by its children. I planted Purple Dome, Vibrant Dome, Alma Potochke, September Ruby and maybe a couple of other cultivars in my butterfly garden. Just seven years later, there's a kaleidoscope of colors out there and none of the plants could honestly be identified as any of the above cultivars.
In other words, unless you are sure you still have the original plant, or a cutting from it, you can't really be sure you have a named cultivar. Even when buying from a nursery, you have to hope they are propagating the plants vegetatively because, if they are growing them from seeds (which, in the case of asters, is a lot cheaper and easier), you aren't truly getting the cultivar you're paying for.
