Well even if you knit the same, once you have worn them they stretch a bit so in future you could look to see which one is which.
I actually knit my socks asymmetrically sometimes. My feet are different from each other, my shoes are as well, the inside of the foot is different from the outside, why would I put different feet into symmetrical and identical socks?
Google 'anatomically correct sock toes' I think you will find a nice blog post on it. Can be done toe up also. If you haven't seen sock toes like that before though they may look a bit odd.