No if you dont work out the bigger muscle that also happens to be weaker it will become even more weaker than the other one. that would cause imbalance in strength which is worse than imbalance in size. i would tell you to focus on dumbells rather than barbell for the simple reason that with barbell the stronger muscle can compensate for the weaker. not telling you to ignore barbell by no means though.
my right pec is smaller than my left and the theory ive heard for this is that since my right side is dominant the muscles on that side are used to way more stimuli than the weaker side and therefor it takes it longer to respond to lyfting. dont know how true this is though. it took me a year of weights for it to even start catching up.