Shortly before the Second World War, Max Friedlander discovered two paintings of emperors, signed and dated AD 1514, in private British collections. He considered them to be independent variations by Dürer of the Nuremberg emperor paintings. The paintings have been controversial among experts ever since. Recently, Franz Winzinger was able to decipher another legend in an x-ray of the Carolus panels, which reveals this painting to be a portrait of Charles IV and not of Charlemagne, like in Nuremberg. From this he concluded that Dürer had changed his concept, that Dürer had initially been commissioned to paint portraits of Charles IV and Sigismund as the two most important emperors for Nuremberg, and that the two paintings were not renamed Carolus Magnus and Sigismund until later. Employing the latest technological examinations, including dactyloscopy, the possibilities and limits of which are discussed, the examination presented in G. Holzheu's article supports Winzinger's theory and corrects his errors.