Do not train 2 times a day. Pro bodybuilders can train 2 times a day, but remember they are a) genetically gifted b) on a LOT of steroids and c) they don't have jobs, so they get plenty of recovery time. 2 times a day for an average person is too much, the general exception being if you are diet and you do cardio 2 or more times a day in addition to training with weights.