Pearl,
My level of gardening skills are demonstrated by the fact that I managed to kill off rhubarb that was cultivated and no doubt enjoyed by the previous owner of my house ,something I understand is really difficult to achieve. In terms of helping you much as I would wish to be able to I am afraid ,as Compo or Truly would have said , I'm a bit of a Tulip in the context of all things horticultural.
From what I can see, Narcissus 'Tresamble' is double headed.