You mean like 90% of other bodybuilders out there? Everyone has slight differences from left and right.
If you pay attention to almost every picture of Arnold, he always displayed his right arm and always has his left arm down in a different pose. He was always known for showing his strengths and hiding his weaknesses. I picked up on this a few years back. Anytime he has a chance to do a bicep pose and show off an arm, it is always the right arm.