ax.fill_between how to blend overlapping colors?

I have a graph shown below.

I've used ax.fill_between to fill under each curve, but I'd like to blend the two colors where the two curves overlap

    x1,y1 = df[Wav1], df[EQE1]
    ax.plot(x1,y1, color="darkcyan")
    ax.fill_between(x1, y1, facecolor='azure')
    
    x2,y2 = df[Wav1], df[EQE2]
    ax.plot(x2,y2, color="firebrick")
    ax.fill_between(x2, y2, facecolor='mistyrose')
   
    ax.scatter(x1,y1, color="darkcyan")
    ax.scatter(x2,y2, color="firebrick")