TST: added test for handling repeated keys when using Series.loc with Multiindex (#47594)

Author: johnmantios

pandas/tests/indexing/multiindex/test_multiindex.py

@@ -213,3 +213,12 @@ def test_subtracting_two_series_with_unordered_index_and_all_nan_index(
 
         tm.assert_series_equal(result[0], a_series_expected)
         tm.assert_series_equal(result[1], b_series_expected)
+
+    def test_multiindex_repeated_keys(self):
+        # GH19414
+        tm.assert_series_equal(
+            Series([1, 2], MultiIndex.from_arrays([["a", "b"]])).loc[
+                ["a", "a", "b", "b"]
+            ],
+            Series([1, 1, 2, 2], MultiIndex.from_arrays([["a", "a", "b", "b"]])),
+        )