The answer is: Its productivity is likely to decrease
If the organization is used to only used one scrum team, the work flow and resources that is used will also only enough for one scrum team.
Because of this, adding two scrum teams would initially only create an abundant of workers. In order to make the additional scrum teams profitable, the company need to also change the number of resources and workflow designs for the scrum team. They would need several time to adjust before finally increase the productivity.