With dual pole breakers (240v) on circuits that also need a common wire it will be more accurate if you use a CT (clamp) on both legs. Reason being that some appliances/equipment require 120v in addition to the 240v. Most newer hot tubs require both 240v & 120v to operation. The 240v for the heater tube and the 120v for the circulation pump and circuit board electronics. My hot tub works in this fashion. When the tub circulates the water only one leg of the dual breaker is registering amp/watts, but when the heater is on both legs of the breaker is registering power. Other dual pole breakers may work the same way it all depends on what you are powering. I have an on demand water heater under my bathroom sink that requires only 240v. In this case I used one CT (clamp) on just one wire (either one works) and set the multiplier to two in the app. I hope this explanation helps.
