Mr. Higgins and his Fold3.com account is a beautiful thing. I remember having to pay fifty dollars just having to find out that information and at fold3.com that gets you a years service. However noticing the ages he listed I'm sure he will tell you e same thing I am about to. It is possible that these are still your man maybe he lied (didn't exactly have a reason to he was within the age requirements) or it could have been another error. One of my ancestors was 17 but claimed to be 18 he served from March 1864 until May 1865 I didn't even catch it until I realized his age never changed the entire time he was in the war. Another thing I had a different ancestor who was named William Jacob Guntharp but went by Jacob on all of his papers. I look more into the draft laws.