If I remember correctly, you get sulfur dioxide from breakdown of excess campden. That is considerably more water soluble than chlorine, so heat conditions that cause the sulfites to leave would have caused the chlorine to leave sooner anyway. You're going to have residual sulfites if you use campden. Sulfites are a better residual in your beer then chlorine and I understand some people want them there for hopes of antioxidant properties. If you're heating your water to 160 degrees in topical homebrew times, the chlorine (not chloramine) is going to be gone as chlorine gas before you mash in, with or without campden. I was just worried I created a situation where the chlorine couldn't leave effectively.
I believe my water has chloramine as well.