Hi,
In your scenario let me clear this point if an employee applies through ESS and it goes for the approval to the Manager then why before the Approval/Rejection of the request Time admin makes an entry directly in system.
The main responsibility of the Time administrator is to check for any errors in the system and if it exist he/she may resolve i.e if while posting there may be some issues etc.
If an entry is already there in back-end and the same is getting approved/rejected by the manager obviously system will throw an error because of the collision in 2001 infotype as per the configuration maintained for the attendance/absence type (Error or Warning message).
The suggestion from point of view is that the process here must be revisited here any one must be approving/rejecting the leave either Manager or Time admin.
Hope this solves your issue there is no other note for overcoming this error as this is standard error thrown by the system.
Regards,
Mithun K
