We often travel with 3, so I often search for availability for 3 adults using the country (e.g. Germany, Spain etc) just to find hotels that offer rooms for more than 2. You will often see upgraded rooms/suites that they will allow 3 or 4 people in... you just then have to decide if the price/location works compared to 2 rooms. To our actual question, I just finished trips with 2 rooms in Malta and London where breakfast was granted for the 2nd room. I have yet to be denied breakfast benefit for a second room.