SQL Server 2012 :: How To Delete Duplicate Rows Present In Parent Table

I have a master table and i need to import the rows into the parent and child table.

Master table name is Flatfile_Inventory
Parent Table name is INVENTORY
Child Tables name are INVENTORY_AMOUNT,INVENTORY_DETAILS,INVENTORY_VEHICLE,
Error details will be goes to LOG_INVENTORY_ERROR

I have 4 duplicate rows in the Flatfile_Inventory which i have already inserted in the Parent and child table.

Again when i run the query using stored procedure,its tells that all the 4 rows are duplicate and will move to the Log_Inventory_Error.

I need is if i have the duplicate rows in the flatfile_Inventory when i start inserting into the parent and child table the already inserted row have the unique ID i must identify it and delete that row in the both parent and chlid table.And latest row must get inserted into the Parent and child table from Flatfile_Inventory.

-- ===============================================================================================
-- STORED PROCEDURE FOR FLATFILE_INVENTORY
-- ===============================================================================================
USE [IconicMarketing]
---=======================================SALES_CURSUR===========================================
--USE IconicMarketing
--GO
DECLARE
@FileType varchar(50) ,
@ACDealerID varchar(50) ,

[code].....