diff --git a/erpnext/selling/doctype/sales_order/sales_order.py b/erpnext/selling/doctype/sales_order/sales_order.py
index b5c5e1b..af3d461 100755
--- a/erpnext/selling/doctype/sales_order/sales_order.py
+++ b/erpnext/selling/doctype/sales_order/sales_order.py
@@ -821,10 +821,10 @@
 		target.stock_qty = (flt(source.stock_qty) - flt(source.ordered_qty))
 		target.project = source_parent.project
 
-	suppliers = [item.get('supplier') for item in selected_items if item.get('supplier') and item.get('supplier')]
-	suppliers = list(set(suppliers))
+	suppliers = [item.get('supplier') for item in selected_items if item.get('supplier')]
+	suppliers = list(dict.fromkeys(suppliers)) # remove duplicates while preserving order
 
-	items_to_map = [item.get('item_code') for item in selected_items if item.get('item_code') and item.get('item_code')]
+	items_to_map = [item.get('item_code') for item in selected_items if item.get('item_code')]
 	items_to_map = list(set(items_to_map))
 
 	if not suppliers: