It just takes sometime to sync... I had a problem a couple of weeks ago, got a reservation from booking, and about 40 minutes later one from airbnb with similar dates. Had to contact my airbnb guest to tell her, she understood. A couple of hours later I got another request for similar dates from HomeAway, had to inform them as well. Next day the booking reservation was cancelled by the guest, and both the other guests had already found new acommodation. Ended up loosing all three reservations. I think they only sync once or twice a day, and that can lead to a few situations.