I am far from a semp expert, but one thing I have learned in my experience with these plants is that it can be very difficult to make a 100% ID due to the many different factors that can affect their appearance (everything from time of year to growing conditions).
Perhaps someone more knowledgeable about this particular species will drop in, but until then here is the link to the Casa entry in the database.
It appears after viewing the page that at one time there were incorrectly labeled Casa being distributed...
Hen and Chicks (Sempervivum 'Casa')
