diff --git a/pandas/tests/frame/test_nonunique_indexes.py b/pandas/tests/frame/test_nonunique_indexes.py
index a8b76f4d85f49..68d0e7cffe7a1 100644
--- a/pandas/tests/frame/test_nonunique_indexes.py
+++ b/pandas/tests/frame/test_nonunique_indexes.py
@@ -513,3 +513,12 @@ def test_set_value_by_index(self):
 
         df.iloc[:, 0] = 3
         tm.assert_series_equal(df.iloc[:, 1], expected)
+
+    def test_masking_duplicate_columns_mixed_dtypes(self):
+        # https://github.com/pandas-dev/pandas/issues/31954
+        df = DataFrame(np.array([[0.0, 1], [2.0, 3]]), columns=[0, 0])
+        expected = DataFrame(
+            np.array([[np.nan, np.nan], [np.nan, 3.0]]), columns=[0, 0]
+        )
+        result = df[df > 2]
+        tm.assert_frame_equal(result, expected)