diff --git a/param/parameterized.py b/param/parameterized.py
index dd8ecdd1..83260056 100644
--- a/param/parameterized.py
+++ b/param/parameterized.py
@@ -2056,6 +2056,8 @@ def _changed(cls, event):
         Predicate that determines whether a Event object has actually
         changed such that old != new.
         """
+        if event.old is event.new:
+            return False
         return not Comparator.is_equal(event.old, event.new)
 
     def _instantiate_param(self_, param_obj, dict_=None, key=None, deepcopy=True):
diff --git a/tests/testwatch.py b/tests/testwatch.py
index e0708a97..e79b955c 100644
--- a/tests/testwatch.py
+++ b/tests/testwatch.py
@@ -183,7 +183,7 @@ def accumulator(change):
         obj.a = 1
         self.assertEqual(self.accumulator, 1)
 
-    def test_triggered_when_unchanged_complex_type(self):
+    def test_untriggered_when_unchanged_complex_type(self):
         def accumulator(change):
             self.accumulator += 1
 
@@ -193,7 +193,7 @@ def accumulator(change):
         obj.a = subobj
         self.assertEqual(self.accumulator, 1)
         obj.a = subobj
-        self.assertEqual(self.accumulator, 2)
+        self.assertEqual(self.accumulator, 1)
 
     def test_triggered_when_unchanged_if_not_onlychanged(self):
         accumulator = Accumulator()