Unfortunately - find duplicates button does not work.
I created two persons with the same Names and Surnames and without any other information, saved this file and tried to find duplicates - nothing has been found...

BlackDog

In the Ages! version 2.01 when i try to find duplicates I receive following error:
Access violation at address 00B645A5 in module 'Ages.exe'. Read of address 458BD881.
May be it will help you to rectify problem.