fix: Don't fetch already discounted invoice
diff --git a/erpnext/accounts/doctype/invoice_discounting/invoice_discounting.py b/erpnext/accounts/doctype/invoice_discounting/invoice_discounting.py
index 64aa4e4..d1ede67 100644
--- a/erpnext/accounts/doctype/invoice_discounting/invoice_discounting.py
+++ b/erpnext/accounts/doctype/invoice_discounting/invoice_discounting.py
@@ -190,9 +190,11 @@
 			customer,
 			posting_date,
 			outstanding_amount
-		from `tabSales Invoice`
+		from `tabSales Invoice` si
 		where
 			docstatus = 1
 			and outstanding_amount > 0
 			%s
+			and not exists(select di.name from `tabDiscounted Invoice` di
+				where di.docstatus=1 and di.sales_invoice=si.name)
 	""" % where_condition, filters, as_dict=1)
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