Gligor already gave a good answer.
I would recommed you that you should film yourself during your workout. maybe you will see some problems, if not, i agree with gligor`s point about the genetic problem. In general i can tell you from my personal experience that i do not think that it is very useful to train the left or the right side isolated, of course you can do it when you achieve for example the one arm pull up, one arm chin up blabla progressions, but you should allways train both sides. in the end it is more ore less just a optical problem, or do you really have the feeling that your right side is also stronger than your left? Check it like Gligor said, if you can not do one arm push ups, do incline push up on a table or negative one arm pull ups.
another good ecercise to find out wheter one body side is really stronger than the other is the side plank with straight arms, because it require mobility, strength and also a good body control