My pecs each definitely have a different shape to them... my right pec (which had gyno surgery) definitely has a nicer rounder shape, even slightly wider i think... however my left pec is a little more thick throughout...
Neither one appears to be much stronger than the other... just how the cards were delt... My pecs have shitty genetics as it is... just keep hammering them and people will be so impressed with your pec size that they won't notice their symetrical imbalance.