Swirl Analysis in an overexpanded CD nozzle
 

I simulated a CD nozzle with swirling flow with converged reaults.However when i extract the velocity preaaure and mach graphs,i see two seperate line for the same plot.I have attached the image.Can someone please help me out why am i observing two plots for the same quantity.Does it have something to do with the swirl phenomenon.I am not having this problem for low swirl numbers.