TSR Integration->Classes & Payroll->Server error is displaying after updating payroll for employees with same name.

Environment - LB (wt-stage)
1] Add a employee with same name through API.
2] Login to the application as a partner.
3] Navigate to "Assign Classes and Payroll Schedule" page.
4] Select newly added employee.
5] Change the payroll only, do not select any class.
6] Click on "Apply" button.

Actual Result:
Server error is displaying but payroll get changed.
Expected Result:
Server error should not be display.
Refer attached screenshot and error log for more details.

Cc: Saurabh Sablaka, Swapnil Pandhare, Prasad Pise, Mahendra Mungase, Rajendra Joshi, Komal Barde, Niteen Surwase