how to plot 2 data sets in the same graph when x axes are different

[#1]

Add your data into single data table, create plot and add two x-axis

Good read regarding plotting in JMP Essential Graphing 

[#2]

Here are 3 ways how you can do it:

How to Overlay scatterplot of data pairs with separate axes 

The 3rd option even works if it's "2 data sets" and not one. But it's very "dirty" - the resulting graph cannot be saved. 

And it is difficult to edit the graph (e.g. adjust the colors).