Only way is to plot both the curves having different scales. That is possible by using both the y axis having different scales as suggested above.

A different solution could be to normalize the values of the data before to plot them:

norm_data=(raw_data-min(raw_data))/max(raw_data-min(raw_data))

this way you obtain the data rescaled in the interval [0,1]

Or, if you want to preserve the relative range of the value if can normalize with:

norm_data=raw_data/max(raw_data)

this way you obtain the data rescaled in the interval [x,1], where x is the ration between the max and min value of your data.

The choice among the two methods depends on the type of the data you are dealing with end on the information that you want to represent in your plot.

Hope this helps