secondary y-axis

Is it possible to overlay two plots with different y-axis limit? I think excel calls this plotting a data set with a secondary y-axis. I want to overlay a bode plot with its coherence and the y-axis limits for the two will be very different. I don't want to plot one above the other with a subplot, but actually overlay them on the same plot.
(and I want to do it on a semilogx).