I'm new with SugarCRM.

Is there anyone who can help me with this matter. I'm having a hard time debugging/tracing in the Merge Duplicate section. I cannot really find what SugarCRM is doing when I clicked Merge Duplicates.

Can anyone tell me what is the PHP file the SugarCRM is processing when I click "Merge Duplicates"?
I'm having a hard time looking for that.

Thanks in advance. Hoping for your reply.