Most times yes a 2 door car will be more expensive to insure especially if the 2 door car is a sports car.
4 door cars that aren't sports cars are usually much cheaper to insure than 2 door cars.
But if the 2 door car is not a sports car then it may not be any cheaper to insure than the 4 door car but it can vary depending on the make, model and year of car and your driving record.