My first post on this was harsh , and I apologise.
I think this may be Bednall Beauty , which has a less symmetrical flower and a smaller eye.
With Dahlias, I usually stake to about one third to one half the height of the plant to keep it more upright, but the bishop is usually pretty well behaved in this regard, and deadhead to extend the flowering period and quality.
However if you dry the seed out you would be amazed at the success from seed , nearly 100%, and the new plants will sometimes be true enough with some surprises.
