Appreciation: Double-flowered rhododendron

Of course I've seen double-flowered azaleas, but I don't remember seeing semi-double blossoms on a non-azalea rhododendron. These are well past their prime, and I don't think I'm going to have a chance to get better photos this year, so here you are. I came up with two possible names - Rhododendron 'Fastuosum Flore Pleno', said by one site to have red dots on the upper petal, but other pages show beige dots, or Rhododendron 'Fastuosum Plenum', or maybe those are similar names for the same thing.

 

I think they are the same plant, synonyms. It's an old hybrid.

www.hirsutum.info/rhododendron/hybrids/detail.php?id=58