Yes, there is an article by Dan Trimmer in which he stated, "This sibling to last year's WILD HORSES is a pale peach with a huge, extremely intense royal purple eye that covers much of the face. The overall effect is much like purple ink spilled on parchment. EGYPTIAN QUEEN can have up to 40 buds and five lateral branches, topped by a terminal Y..."
I have both Egyptian Queen and Wild Horses in my gardens and, despite being sibs, there are definite differences. Egyptian Queen is slightly taller, has slightly better branching and is less 'cream' and more 'white' than Wild Horses. Both do extremely well here in my zone 3 gardens, bloom reliably every year and are quite hardy. Despite their similarities, they each have earned their own place in the gardens.