Restricting expense approval to expense entry user

Hi Guru's,

As per our current setup expense report approvals for employee are in 2 steps

1- employees direct manager

2- department manager based on limits- this is a customization - we have a lookup with approvers for each department

However in few cases when employee AA submits expense report it goes to his manager BB

once approved by BB

it goes to AA again since he is department manager.

Can we restrict this anyway. Can i make sure if one of approver is employee itself who enters then no need for approval or auto approve.

Thanks,
Satish