The Masses of Cardoso and his Portuguese contemporaries follow an interesting pattern in their Kyries, providing two distinct polyphonic settings of the Christe. This Kyrie–Christe–Christe–Kyrie sequence is only exceptionally found in the Spanish and Roman etc. schools, but was standard on the Iberian Peninsula in the 16th and early 17th centuries. What is the significance of this and how does it affect our approach to performance?