Integration-To reject duplicate records from the file

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My requirement is that I am getting the header and line details in a single file for AP invoice creation. Like in this format.

BusinessUnit,LegalEntityName,InvoiceNumber,Currency,InvoiceAmount,TransactionDate,InvoiceDescription,PaymentTerms,ItemNumber,LineExpenseAmount,LineDescription,Company,NominalAccount,CostCenter
UK Operations,UK Operations,INV-90909,GBP,989,2020-06-12,Standard unmatched Invoice,Immediate,10,989,Standard Line,P1010,0001,CC00000
UK Operations,UK Operations,INV-90910,GBP,1020,2020-06-14,Standard unmatched Invoice,Immediate,10,990,Standard Line,P1010,0001,CC00000
UK Operations,UK Operations,INV-90910,GBP,1020,2020-06-14,Standard unmatched Invoice,Immediate,11,30,Standard Line,P1010,0001,CC00000

 

Problem is that for multiple lines, the same header information is also repeated in the file. And I have to create two separate files for Header and Line in AIC. So how can I reject those repeating Header information in AIC.