The fact that each set consists of three ‘identical’ coins
means that if the original owner of Set #23 (coins #023
(gold), #123 (silver), and #223 (black)) sold one of the
coins to a buyer who had decided to fund it, anyone
with either of the other coins could redeem the funds
without the original funder’s knowledge. The entire set
must be ‘together’ for the owner to ensure security.