People often assume that because there are two voltage sources and there are two columns of breakers in the panel, then the breakers on one side are powered by one voltage source and the breakers on the other are powered by the other voltage source, and this isn't true. That would present a safety risk because it wouldn't allow you to use double breakers to disconnect BOTH voltage sources from the appliance when you trip it's breaker.

Different panels are made differntly, and it's the buss bars inside the panel that determine what gets connected to what, but for safety reasons, it's important to connect 240 VAC appliances like stoves, dryers and central air conditioners to double breakers installed on the SAME SIDE of a panel. That way, you can't trip the power off to one voltage source without tripping it off to both voltage sources so that the appliance is safe to work on.