Anna - There will never be a resolution here. Don't make yourself crazy over it. There are those who say these are two different varieties and those, like me, who will swear on a stack of Fritos that they are the same. I grow Satan, a cutting from the plant seen in Dr. Brown's book and given to me by Jesse Durko. I have seven different plants in various areas of the garden, all cuttings from the original one, all different in terms of leaf size and shape, color, and variegation. I have been given plants that were certified as Irene Kingsley and they have grown into the exact same plant as at least one or two of my Satans.