diff --git a/ceilometer/agent/base.py b/ceilometer/agent/base.py
index bbfbe6bb8..ac9a843ed 100644
--- a/ceilometer/agent/base.py
+++ b/ceilometer/agent/base.py
@@ -65,6 +65,7 @@ class Resources(object):
         self._resources = []
         self._discovery = []
         self.blacklist = []
+        self.last_dup = []
 
     def setup(self, pipeline):
         self._resources = pipeline.resources
@@ -139,10 +140,32 @@ class PollingTask(object):
                     candidate_res = (source_resources or
                                      pollster_resources)
 
-                    # Exclude the failed resource from polling
+                    # Remove duplicated resources and black resources. Using
+                    # set() requires well defined __hash__ for each resource.
+                    # Since __eq__ is defined, 'not in' is safe here.
+                    seen = []
+                    duplicated = []
+                    polling_resources = []
                     black_res = self.resources[key].blacklist
-                    polling_resources = [
-                        x for x in candidate_res if x not in black_res]
+                    for x in candidate_res:
+                        if x not in seen:
+                            seen.append(x)
+                            if x not in black_res:
+                                polling_resources.append(x)
+                        else:
+                            duplicated.append(x)
+
+                    # Warn duplicated resources for the 1st time
+                    if self.resources[key].last_dup != duplicated:
+                        self.resources[key].last_dup = duplicated
+                        LOG.warning(_(
+                            'Found following duplicated resoures for '
+                            '%(name)s in context of %(source)s:%(list)s. '
+                            'Check pipeline configuration.')
+                            % ({'name': pollster.name,
+                                'source': source_name,
+                                'list': duplicated
+                                }))
 
                     # If no resources, skip for this pollster
                     if not polling_resources:
diff --git a/ceilometer/tests/agent/agentbase.py b/ceilometer/tests/agent/agentbase.py
index d4b432896..711013392 100644
--- a/ceilometer/tests/agent/agentbase.py
+++ b/ceilometer/tests/agent/agentbase.py
@@ -446,6 +446,10 @@ class BaseAgentManagerTestCase(base.BaseTestCase):
             self.assertEqual(set(self.Discovery.resources),
                              set(self.Pollster.resources))
 
+        # Make sure no duplicated resource from discovery
+        for x in self.Pollster.resources:
+            self.assertEqual(1, self.Pollster.resources.count(x))
+
     def test_per_pollster_discovery(self):
         self._do_test_per_pollster_discovery(['discovered_1', 'discovered_2'],
                                              [])
@@ -455,6 +459,14 @@ class BaseAgentManagerTestCase(base.BaseTestCase):
         self._do_test_per_pollster_discovery(['discovered_1', 'discovered_2'],
                                              ['static_1', 'static_2'])
 
+    def test_per_pollster_discovery_duplicated(self):
+        self._do_test_per_pollster_discovery(['dup', 'discovered_1', 'dup'],
+                                             [])
+
+    def test_per_pollster_discovery_overridden_by_duplicated_static(self):
+        self._do_test_per_pollster_discovery(['discovered_1', 'discovered_2'],
+                                             ['static_1', 'dup', 'dup'])
+
     def test_per_pollster_discovery_caching(self):
         # ensure single discovery associated with multiple pollsters
         # only called once per polling cycle
@@ -492,6 +504,10 @@ class BaseAgentManagerTestCase(base.BaseTestCase):
         self.assertEqual(set(static_resources + discovery),
                          set(self.Pollster.resources))
 
+        # Make sure no duplicated resource from discovery
+        for x in self.Pollster.resources:
+            self.assertEqual(1, self.Pollster.resources.count(x))
+
     def test_per_pipeline_discovery_discovered_only(self):
         self._do_test_per_pipeline_discovery(['discovered_1', 'discovered_2'],
                                              [])
@@ -504,6 +520,10 @@ class BaseAgentManagerTestCase(base.BaseTestCase):
         self._do_test_per_pipeline_discovery(['discovered_1', 'discovered_2'],
                                              ['static_1', 'static_2'])
 
+    def test_per_pipeline_discovery_discovered_duplicated_static(self):
+        self._do_test_per_pipeline_discovery(['discovered_1', 'pud'],
+                                             ['dup', 'static_1', 'dup'])
+
     def test_multiple_pipelines_different_static_resources(self):
         # assert that the individual lists of static and discovered resources
         # for each pipeline with a common interval are passed to individual