ORC - Merge candidate hired manually with candidate hired through ORC

Summary:

We want to merge the candidate hired manually through My client groups> New person Hire an Employee with the candidate applied through ORC.

Content (required):

We have a scenario where the candidate is applied through ORC and when he reached offer stage the HR person without knowing that the candidate is applied through ORC and created the candidate manually through Core HR - Hire a new employee.

Now the candidate is exist in system which is created manually.

But now from ORC this candidate is in Offer stage and we moved this candidate to Core HR by "Move to HR", but as though the person is already available in system but system didn't identified this candidate as duplicate.