The buck looks plenty young so try an wait on him till next year. If he still don't have a matching side then you should take him as a cull buck. Some times bucks hit their horns on some thing or lay on them while they are in velvet. They get weird little curves and things most would call character to their rack because of it. some times they just don't take good enough care of it and they break some tines off. I saw it happen to a buck I was watching *not quite grown yet* and I was all upset cause he came out with a messed up rack. Till I found some velvet tines in some brush, then I knew what was up. Yours could have done the same or he could have funky gene's or maybe the injury has stiffeled his growth which can happen too. definitely wait on him for next year.