In this study two cord blood collections will be used to increase the number of cord blood cells you will receive on transplant day. We call this a "double unit" cord blood transplant. A previous study suggests double unit cord blood transplant may have a better result. The main purpose of this study is to find out how good a cord blood transplant using two cord blood collections from two different babies is at curing you of your cancer. Double unit cord blood transplants are now being studied as a way to increase the number of cord blood cells given to bigger children and adult patients.