N4101120 business funcation can be used to create records in F41021 & F4111, if you are trying to create Item without using P4101 or R4101Z1I.
The issue with this business function that it do not check for the Item Ledger if record is already present or not. It creates new record in F4111. To avoid this pass the Program ID as EP4600 so that it will not execute the BSFN which creates the record in F4111. And use other BSFN to create record in F4111.