Draw two figures with separate x and y axis

This script plots two sets of 1D data on the same figure.

This script plots two sets of 1D data on the same figure with two separate axis and with the same gridding.
The code also checks if the x-axis data are the same, if the x-axis data
are not the same, it draws an additional x-axis on the top of the figure.
The two sets of data with their axes are drawn with two colors for ease of reading