Not true, Jim. It is redundant, in that the second rope acts as a backup for the first. Say you're climbing on a double-rope setup and are 60' or 75' up with ropes clipped alternately to 5 or six pieces or pro. Due to rockfall from above, a baseball sized rock hits one of your ropes and chops through to the core. Your other rope is intact and you can finish the pitch knowing that you have one solid rope left. If you were in this same situation with a single it would be really bad, with a redundant, double rope system you can escape in relative safety.