adjoining

A woman says : Could you please rent us two rooms with an adjoining bath?

Two rooms with an adjoining bath : does it mean that there's only one bathroom for the two rooms or a bathroom for each room (that is, 2 bathrooms?)

This isn't the usual way to express it in English. To my mind, it sounds as if they want two rooms with access to one bathroom close by (i.e. not on another floor or down a long corridor).

Normally these days, if you want a room with its own bathroom (so you don't have to go out of the room) you ask for a room with an ensuite/with a bathroom ensuite (ensuite usually written as one word in English), or, in this case, two rooms with ensuite bathrooms (i.e. 1 ensuite each).

Others might read it differently.

It comes from an old American film.

I read it as meaning, there are two rooms, with one bathroom. The bathroom has doors leading into both of the rooms (adjoining).

I wouldn't disagree with SDR. Now we know it's from an old American film, she is better placed than me to get the sense. Maybe two rooms with a bathroom in the middle accessible to each room was more common in those days, but this sort of room lay-out is a bit unusual today. If you're interested, we call it a "Jack and Jill bathroom".

Enquiring Mind said:

If you're interested, we call it a "Jack and Jill bathroom".

Love it!

A Jack and Jill bathroom is also called a Hollywood bathroom.

I've never heard of any type of lodging establishment with that sort of arrangement so I think it would be very unusual to ask for it so matter-of-factly. You can often get "adjoining rooms" but they are connected by a doorway not by a bathroom.

I would assume that it means:
Two (rooms with adjoining bath) not (two rooms) with adjoining bath.

This is an old movie obviously as having a bathroom in the room is the norm in modern American hotels. If this is not the case, you would be told that the bathroom was down the hall or shared, but I would only expect this at an old inn or staying in a house. We don't use the word "ensuite".