If they view your profile on the AirBNB website, both of your listings should appear in the lower left portion of the screen. They can then click the second listing to see all of the details.
I have tried to explain to guests via message how to build the URL for a listing, with no success. Turns out, most people do not understand how a URL is built.
Your other option is send them the title of the listing and suggest that search for "AirBNB yourTownName YourListinTitle" and generally, your listing should be the first one in the resulting list. You do have to use the word "search." Google will get stripped out with the "HIDDEN CONTENT" substitution.