Hi Charvi,
Your requirement seems to be a bit weird, as Direct debit run is done to clear the outstanding receivables.Not sure about the business rationale for your above requirement.
However, I think it can be achievable through following Config.
IMG-->Financial Accounting-->Contract Accounts Receivable and Payable-->Basic Functions-->Open Item Management-->Clearing Control-->Define Specifications for Clearing Types--->Define Defaults for Incoming Payments
Click on New Entries. Select clearing type as 06. Don't give anything in General clearing variant and value 2 in the post on acct field and press save.
Hope it helps...
Thanks,
Amlan