Once you receive confirmation that the contacts were imported successfully, go back to the CheckMarket tool and open the survey you’ve added these contacts to. You will now see multiple records for the same person.
When you launch your survey, this person will receive multiple invitations, equivalent to the number of times they appeared on your contact list. If the survey was already live and you’re simply adding new addresses to it, only the new contacts will receive an invitation.
In my example, Mr Johnson will receive two invitations.