Ceteris paribus, Subj. 2 will definitely be bigger. Your body is always trying to adapt to the workload given it, so once Subj. 1's body has adapted to 100 lbs., he won't grow past what his body needs to lift 100 lbs. Subj. 2 will be constantly upping the weight, forcing his body to adapt to each step, then raising the bar a little more - progression, basically. So yes, he'll grow more.