Paragraph 3.49 in Volume 2 of AD B states; Bedrooms should not contain more than one bed (this includes a double bed). This is for a design, without sprinklers, relying upon fire-resisting construction to protect occupants that are remote from the seat of the fire.
The research report Sprinkler Effectiveness in Care Homes has shown that people who are in intimate contact with a fire, for example where clothing or bed linen is alight, are unlikely to benefit from the operation of sprinklers. However, where sprinklers are provided, people who may be in the same room but not in intimate contact with the fire (for instance in another bed) will have an increased chance of survival.
It is not the intention of the Approved Document to separate couples who happen to live in a care home by insisting that they sleep in separate beds.