Bodybuilders train with weights in order to develop a nice balanced-looking physique. However, at some stage in your lifting career you might notice that certain muscles may be uneven. Left biceps or triceps may be not the same size or shape as the right, etc. These imbalances are usually more noticeable early in your bodybuilding career.
Since I have also experienced this, I would like to offer some pointers.
There are few things that you can do to improve uneven muscles.
Train each muscle individually using unilateral exercises. By doing so, you concentrate on each muscle individually and you prevent the stronger muscle from doing most of the work. This means choosing mostly dumbbells over barbell when performing exercises for your uneven muscles.
When I started to rectify an imbalance in my triceps I performed unilateral exercises. I found that by doing the exercise first on my weaker side I was able to put more energy towards it.
Another problem that may lead to developing unbalanced muscles could be your posture. If you have imbalanced muscles that concern you, you may need to check for postural issues as well.
From my own experience, training over time will even out the muscles that were once unbalanced. So, just give it a time and meanwhile implement some of the above mentioned methods.