LTMC object, PM - General maintenance task list

Hello Experts,

I have a requirement to upload LTMC object (PM - General maintenance task list),

As sub operation is not included in standered template, So I have added it into LTMOM Source field and done mapping.

Now the Sub operation field is available in LTMC upload template but once i am trying to upload three line items with operation 0010 and sub-operation 0011&0012 it gives me error. As sub-operation is there system should not consider it as dulicate entry

System is allowing me to replicate the same in T-code IA05, But not in LTMC.

Please let me know what I am missing. Using S/4 2020 system

Error: (Task list - operation/activity contains records with duplicate keys:

Message no. DMC_RT_MSG625

Check whether there is any typo in sheet Task list - operation/activity. Remove records with duplicate keys.)