Airbus procedure is for the CM2 to carry out the ECAM and EVAC paper procedure on his own without confirming till EVAC REQUIRED. CM1 only evaluates the evacuation decision. The reason is it is possible that ATC is giving some valuable information regarding the fire or the fire chief may be trying to talk to the captain. If both pilots are involved in the EVAC procedure then it may delay the execution and evacuation. A few airlines require both to involve in the procedure.