I have Polydactyly, 6 toes on one foot, is this common?
No, I think this is very rare. Is it just soft tissue that can be removed?
no it a real toe with bone and nail and everything
Has this caused any problems for you?
no pain, but just embarrassment to go barefooted and need a wider shoe for it.
Well I can see it being embarrassing to be barefoot. On the other hand shoes can cause problems such as bunions and hammer toe, especially if you have an extra toe. 
yea,  I always have to buy a wider shoe to accommodate for my extra toe
Good idea because if you smash all your toes into too narrow a shoe, the toe can become permanently bent, resembling a hammer. That's hammer toe.