Why don't we want the dead heads to turn into seed pods? Won't this just produce more plant's? Or, what are the seeds and what do they produce?
You could let the flower go to seed but this will inhibit repeat bloom as the plant channels energy into seed formation. It is very easy to divide the tubers after the leaves die back if you wish to propagate more plants. Northern gardeners have to dig up tubers in the fall and store them as they won't overwinter north of zone 7. You can grow calla from seed but it takes 3 years to reach blooming size.