The merge contacts job eliminates the duplicate contact record and retains the master contact record. If the duplicate contact record is associated with an account record, the
Allow users to relate a contact to multiple accounts
account setting determines whether to associate the account record with the master contact record.
If this account setting is disabled, the merge contacts job eliminates the duplicate contact record and its association with the account record. If you enable this account setting, the merge contacts job eliminates the duplicate contact record and then associates the account record with the master contact record. By default, this account setting is disabled.