This is most often the case of digital finger printing; the client will often have this enabled for their projects.
This service is intended to stop duplication or those attempting to do the survey more than once. It will also do IP address validation. This process is not 100% accurate, so if you are repeatedly flagged as a Duplicate and you definitely haven’t done the survey before please create a support ticket and we’ll investigate.
As we don't write the surveys, members of other survey providers will be invited via others first. This will limit your opportunity to earn the highest incentive for the exact same survey.