When setting up employees you may have inadvertently assigned the same to more than one employee, or you did not enter the number, leaving it as zeroes. To report employees with the same use the Find Duplicate SSN/SIN feature.
The Duplicate SSN/SIN Listing report helps you identify employees who have been assigned the same . You should assign a unique to each employee before you start year-end processing and reporting, such as generating T4 or Relevé 1 slips.