This is not a hybrid but an outcross of two unrelated cultivars of roths. I have seen it made with 'Rex' as the pod parent, not sure if 'MM' was used as pod (although it is reasonable if it were).
It was made by the Orchid Zone and has brought the flower quality of that species to a whole new level. Say what you will about that sanderianum fiasco they had, but these are some spectacular roths...