It seems there are some issues with duplicate detection. Testing it out I was expecting to be able to update the candidates profile from Linkedin and in doing so to connect the Linkedin URL. Alas It did not find the candidate at all and the only option was to create one (A duplicate).

This is despite the candidate with the same name, spelling, location, email and attached CV being in the system.

On a separate but related note: In other systems historically we have been able to set which combinations of data points equate to a duplication. This is so that it can be customised for Head-hunters as apposed to Agency / CV board recruiters who will often have the candidates email ID where as a name gathering, head-hunter would not.