Such a large service has no algorithm that solves the problem of double spending. Its very sad, although, I hope that the developers will implement such an algorithm into the platform in the near future. But all in all I really like the CREDITS project!
Apparently, youve read the white paper of the project not carefully. How could you imagine the operation of such a service without such an algorithm? If it werent implemented, there would be huge confusion and a problem with fraud. That is why it has been developed long ago.