Strange cards!

We have several booking.com reservations in this weekend, all booked against the same card which is un-chargeable. As far as we're aware we have never seen this type of booking before and wondered whether it was a new procedure? Our booking.com reservations always come with a VCC or the guests card attached, this new card comes with notes stating "do not charge this card". But how does this work in terms of late cancellations and no shows?