Jan de Gier - University of Melbourne We derive a joint universal KPZ current distribution from first principles in the integrable two-species Arndt-Heinzel-Rittenberg (AHR) model. This result follows from exact multiple contour expressions for the Green's function and a joint current probability, and a subsequent asymptotic analysis of these integrals via Fredholm determinant techniques. It is the first such result for a two-species Markov chain, confirming heuristic predictions from nonlinear fluctuating hydrodynamics (NLFHD).