In order to compare two wave profiles from XPAN computation do the following:
1 - Select the first design that you want to show in the table of results, click on show results button (a computer symbol with an eye in the middle);
2 - Go to the plot viewer and lock the design by clicking on the lock symbol upper left corner of the plot;
3 - Go to the design you want to compare with, select and also show the results (should be already triggered);
4 - Go back to the plot viewer and your two results should be there;
5 - Edit the plot settings so that you can distinguish between the designs.
Here is an example of two compared wave profiles: https://imgur.com/1rRPQ5A
Note the red lock button in the upper left corner.
Let us know if this solved your doubt.