Restrict self GL batch approval

We are using Oracle EBS R12.2.8 application( General Ledger) and Using oracle Standard Workflow for GL batch approval . We have restricted Self GL batch approval by setting Profile Option "Journals: Allow Preparer Approval" with value "No". But its not working in below scenario. Do we have any solution for the same ?

Scenario: Example:- Mr.jack is manager of Mr.Som, Mr.Jack is having rights to approve the GL batch submitted by Mr.Som as per HRMS setup. When Mr.Jack set "Vacation Rules" and delegate all GL batch approval notification to his assistant Mr.Som. then Mr.Som is able to approve the all notifications received form Mr.Jack. But problem is that when Mr.Som prepare his own batch and submit it then it delegate to him due to Vacation rule setup. And We want to restrict Mr.Som from approving his own GL batch, System should restrict this.