Clare, the business about the duplicate listing and different host name is all phony.!!! THERE IS NO DUPLICATE LISTING!!! (There is no other host copying their listing!! )THis is all a fiction by the hacker to create a sense of alarm in the host so they fall prey to the hacker.
The whole point of the hacker is to come up with some ploy (in this case, the fiction that someone else copied their listing -- in other cases, it has been a ploy to ask host to go to a link that will supposedly help them be a superhost in 4 days) to get the host to do what they want, which is to visit their link and log in. SO with this fiction, they create a sense of urgency and alarm in a host, so that they don't think about what they are doing, but end up logging into a fake Airbnb page because they think someone else copied their listing.
Point being, the story that is presented is beside the point, it is all fake. The whole point is that you are being sent a link that the hacker wants you to think is the AIrbnb site so you log in. THey will come up with a thousand different ways to get you to do that. You need to see through all this and realize what they are trying to do. Eg you need to not miss the forest (the hacker luring you into the phishing site) for the trees (the particular one of any of a thousand fictional stories the hacker may present in order to get you to do that).
To make the host believe the "guest" more readily, hackers will often use AIrbnb accounts that they have already hacked into, to contact other hosts. That way, the host thinks the person contacting them "must be real" because they see the person has 23 reviews, or whatever, and a real listing with real reviews. That guest is real, but the person contacting you is not that guest, it's the hacker who hacked their account and is using their account now to lure others into their phishing site so that they can expand their arsenal of hacked accounts.
I'm not clear how Sophie got the message, whether through Airbnb messaging (eg as we do from any guest, when they inquire with us) or whether she got this to her private email only. @Sophie0 can you let us know how you got this message? In your Airbnb account or on your private email only?