Candidates may apply for multiple positions at your company. For each position that an applicant applies to a separate profile will be created based on the email address used.
If an applicant applies for Position A and Position B, they will have two profiles in your account - one for each job. Any interaction with the applicant will be unique on each profile. For example, when you fill a score card for applicant in Position A, nothing will update in Position B.
Instead, it will be shown in applicant profile that there are potential duplicates. These are identified using matching email address.