Hi @Bronwen3
I travel a lot with my mother, so I always look for places with 2 beds / 2 bedrooms / bed + sofabed.
I allways tell the host that I am traveling with my mum and, because of that, we need the 2 beds made up.
Same happened last year, when we traveled in 4 people (1 couple + 2 friends). we looked for places with 3 bedrooms, told that it would be 4 people, but we needed 3 beds made.
Not once we were charged. Maybe they assumed that it would be less people having showers / etc?
If you are renting a place with 2 beds, I would assume that it is because you need the 2 beds, otherwise, I would look for a place with only 1 bed, right?