Answered How to import multi line transactions into QuickBooks? J Jennifer Allen started a topic over 6 years ago How to import multi line transactions like Invoice with Line items ?
Invoice No or Ref No column is used to group your multiline transactions ( 2 products / service ) in same invoice.
So please provide unique value for that row to group invoices . You can learn more at https://support.saasant.com/support/solutions/articles/14000053173-multi-line-transactions-import-made-easy-
Please refer this screenshot of the sample Invoice File