Q.Calla white lily double head
I have a white lily plant which i think is a calla lily it has a double head on one stem. Is this unusual?

I have been growing calla outdoors for years. This year for the first time, I had one bloom that was "double" or partially fused. I've seen other plants produce mutations that were one-off abnormalities. It serves as a reminder of just how complex plants are. A genetic miss-step at any point from seedling to flower is possible. It might be stressful conditions, a pest, virus or, as I call it, serendipity. The following article discusses fasciation in plants: https://www.gardeningknowhow.com/plant-problems/environmental/fasciation-in-flowers.htm