Critical Illness insurance is a fixed benefit product. You can claim the entire Sum Assured from all CI insurance policies that you have taken on your life. However, it is advisable to inform your Insurer (at the time of filling the proposal form for the new CI policy) about any other active CI policy that you have on your life. This will steer you clear of any confusion/questions at the time of a claim. Hope I have made my point. Please feel free to revert if you have any follow up questions.