This is an old type of scam attempt against hosts but it bears repeating since it is resurfacing.
Hosts may receive this as an inquiry. It is a scam attempt to lure a curious host into going to a non-Airbnb website where they will be asked to provide a user ID and password to access the information about the "other listing". It is nothing more than an attempt to obtain host's Airbnb login credentials then access and compromise their account. There is no other listing. It is a scam.