Bill designed by each bank!?

While waiting for bus to the next destination, Glencoe, I withdrew some money. We have noticed design of the bills is different; one for up is the one I had at Forex Lund by exchanging, which looks like issued by Bank of Scotland while another for down is the one I withdrew at a cash machine at Portree, which looks like issued by the Bank running that ATM. I even suspected counterfeit but I managed to use them without any problem at a shop in Glencoe.