Are there any issues regarding being rated for the left or right seat - in the US?
In my country, you have to be certified to fly from the right seat to log any time. Otherwise, with two students flying togther, the only time the right student may take the controls, is when the PF takes a drink of water, or the likes. Common, but also illegal of course.
We also have problems with students who want to share multi-instrument time. Even when one student gets rated to fly from the right seat, intending to log 2IC time, the flight school's SOPs may not permit any logging of 2IC time if one pilot is not an instructor.