diff --git a/erpnext/regional/report/hsn_wise_summary_of_outward_supplies/test_hsn_wise_summary_of_outward_supplies.py b/erpnext/regional/report/hsn_wise_summary_of_outward_supplies/test_hsn_wise_summary_of_outward_supplies.py
new file mode 100644
index 0000000..86dc458
--- /dev/null
+++ b/erpnext/regional/report/hsn_wise_summary_of_outward_supplies/test_hsn_wise_summary_of_outward_supplies.py
@@ -0,0 +1,89 @@
+# Copyright (c) 2021, Frappe Technologies Pvt. Ltd. and contributors
+# For license information, please see license.txt
+
+
+from unittest import TestCase
+
+import frappe
+
+from erpnext.accounts.doctype.sales_invoice.test_sales_invoice import create_sales_invoice
+from erpnext.regional.doctype.gstr_3b_report.test_gstr_3b_report import (
+	make_company as setup_company,
+)
+from erpnext.regional.doctype.gstr_3b_report.test_gstr_3b_report import (
+	make_customers as setup_customers,
+)
+from erpnext.regional.doctype.gstr_3b_report.test_gstr_3b_report import (
+	set_account_heads as setup_gst_settings,
+)
+from erpnext.regional.report.hsn_wise_summary_of_outward_supplies.hsn_wise_summary_of_outward_supplies import (
+	execute as run_report,
+)
+from erpnext.stock.doctype.item.test_item import make_item
+
+
+class TestHSNWiseSummaryReport(TestCase):
+	@classmethod
+	def setUpClass(cls):
+		setup_company()
+		setup_customers()
+		setup_gst_settings()
+		make_item("Golf Car", properties={ "gst_hsn_code": "999900" })
+
+	@classmethod
+	def tearDownClass(cls):
+		frappe.db.rollback()
+
+	def test_hsn_summary_for_invoice_with_duplicate_items(self):
+		si = create_sales_invoice(
+			company="_Test Company GST",
+			customer = "_Test GST Customer",
+			currency = "INR",
+			warehouse = "Finished Goods - _GST",
+			debit_to = "Debtors - _GST",
+			income_account = "Sales - _GST",
+			expense_account = "Cost of Goods Sold - _GST",
+			cost_center = "Main - _GST",
+			do_not_save=1
+		)
+
+		si.items = []
+		si.append("items", {
+			"item_code": "Golf Car",
+			"gst_hsn_code": "999900",
+			"qty": "1",
+			"rate": "120",
+			"cost_center": "Main - _GST"
+		})
+		si.append("items", {
+			"item_code": "Golf Car",
+			"gst_hsn_code": "999900",
+			"qty": "1",
+			"rate": "140",
+			"cost_center": "Main - _GST"
+		})
+		si.append("taxes", {
+			"charge_type": "On Net Total",
+			"account_head": "Output Tax IGST - _GST",
+			"cost_center": "Main - _GST",
+			"description": "IGST @ 18.0",
+			"rate": 18
+		})
+		si.posting_date = "2020-11-17"
+		si.submit()
+		si.reload()
+
+		[columns, data] = run_report(filters=frappe._dict({
+			"company": "_Test Company GST",
+			"gst_hsn_code": "999900",
+			"company_gstin": si.company_gstin,
+			"from_date": si.posting_date,
+			"to_date": si.posting_date
+		}))
+
+		filtered_rows = list(filter(lambda row: row['gst_hsn_code'] == "999900", data))
+		self.assertTrue(filtered_rows)
+
+		hsn_row = filtered_rows[0]
+		self.assertEquals(hsn_row['stock_qty'], 2.0)
+		self.assertEquals(hsn_row['total_amount'], 306.8)