You can configure the internal settings and default behavior for contacts and custom objects.
You can configure the following internal settings:
Configure Default Duplicate Check and Merge Batch Job Settings
You can change the default duplicate check and merge batch job settings.
To enable the deletion of previously merged duplicate pairs from the duplicate table and pair new records with the survivor of the previous merge process, set the
Duplicate check job reassign master
value to true. Default is false.
The following sample code enables the deletion of previously merged duplicate pairs for contacts and custom objects: