I got this machine yesterday. It's from the ferry between Denmark and Norway, placed by bell casino. It has two extra cards mounted in the back of the machine, communicating with an normal coin acceptor and a bill acceptor. The coin acceptor takes 5kr, 10kr and 20kr coins, adding them as credit. The bill acceptor takes 50kr, 100kr and 200kr notes. You can still add 1kr coin as normal to the machines normal coin acceptor. It still pays out as normal.
I have never seen cards like this before, and wonder if it's rare. Please comment.