diff --git a/flusher.go b/flusher.go
index b47292695..334e515ae 100644
--- a/flusher.go
+++ b/flusher.go
@@ -183,7 +183,19 @@ func (s *Server) flushSink(
 					maxTagLengthCount += 1
 					continue metricLoop
 				}
-				filteredTags = append(filteredTags, tag)
+
+				replaced := false
+				for i, ft := range filteredTags {
+					if ft[0:len(k)] == k {
+						filteredTags[i] = tag
+						replaced = true
+						break
+					}
+				}
+
+				if !replaced {
+					filteredTags = append(filteredTags, tag)
+				}
 			}
 
 			if sink.maxTags != 0 && len(filteredTags) > sink.maxTags {
diff --git a/flusher_test.go b/flusher_test.go
index fb884043b..1dba8abf5 100644
--- a/flusher_test.go
+++ b/flusher_test.go
@@ -972,6 +972,308 @@ func TestFlushWithAddTags(t *testing.T) {
 	})
 }
 
+func TestFlushWithAddTagsDedupes(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	channel := make(chan []samplers.InterMetric)
+	mockStatsd := scopedstatsd.NewMockClient(ctrl)
+	server, err := NewFromConfig(ServerConfig{
+		Logger: logrus.New(),
+		Config: Config{
+			Debug: true,
+			Features: Features{
+				EnableMetricSinkRouting: true,
+			},
+			Hostname: "localhost",
+			Interval: DefaultFlushInterval,
+			MetricSinkRouting: []SinkRoutingConfig{{
+				Name: "default",
+				Match: []matcher.Matcher{{
+					Name: matcher.CreateNameMatcher(&matcher.NameMatcherConfig{
+						Kind: "any",
+					}),
+					Tags: []matcher.TagMatcher{},
+				}},
+				Sinks: SinkRoutingSinks{
+					Matched: []string{"channel"},
+				},
+			}},
+			MetricSinks: []SinkConfig{{
+				Kind:    "channel",
+				Name:    "channel",
+				AddTags: map[string]string{"foo": "bar", "anotha": "one"},
+				MaxTags: 5,
+			}},
+			StatsAddress: "localhost:8125",
+		},
+		MetricSinkTypes: MetricSinkTypes{
+			"channel": {
+				Create: func(
+					server *Server, name string, logger *logrus.Entry, config Config,
+					sinkConfig MetricSinkConfig,
+				) (sinks.MetricSink, error) {
+					sink, err := NewChannelMetricSink(channel)
+					if err != nil {
+						return nil, err
+					}
+					return sink, nil
+				},
+				ParseConfig: func(
+					name string, config interface{},
+				) (MetricSinkConfig, error) {
+					return nil, nil
+				},
+			},
+		},
+	})
+	assert.NoError(t, err)
+	server.Statsd = mockStatsd
+
+	wg := sync.WaitGroup{}
+	wg.Add(1)
+	go func() {
+		server.Start()
+		wg.Done()
+	}()
+	defer func() {
+		server.Shutdown()
+		wg.Wait()
+	}()
+
+	mockStatsd.EXPECT().
+		Count(
+			gomock.Not(anyOf("flushed_metrics", "dropped_metrics")), gomock.All(), gomock.All(), gomock.All()).
+		AnyTimes()
+	mockStatsd.EXPECT().
+		Gauge(
+			gomock.Not("flushed_metrics"), gomock.All(), gomock.All(), gomock.All()).
+		AnyTimes()
+	mockStatsd.EXPECT().
+		Timing(
+			gomock.Not("flushed_metrics"), gomock.All(), gomock.All(), gomock.All()).
+		AnyTimes()
+
+	t.Run("WithAddTags", func(t *testing.T) {
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:skipped",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_name_length",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_tags",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_tag_length",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(1), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:flushed",
+			"veneurglobalonly:true",
+		}, 1.0)
+
+		server.Workers[0].PacketChan <- samplers.UDPMetric{
+			MetricKey: samplers.MetricKey{
+				Name: "test.metric",
+				Type: "counter",
+			},
+			Digest:     0,
+			Scope:      samplers.LocalOnly,
+			Tags:       []string{"foo:baz"},
+			Value:      1.0,
+			SampleRate: 1.0,
+		}
+
+		result := <-channel
+		if assert.Len(t, result, 1) {
+			assert.Equal(t, "test.metric", result[0].Name)
+			if assert.Len(t, result[0].Tags, 2) {
+				assert.Equal(t, "foo:bar", result[0].Tags[0])
+			}
+		}
+	})
+
+	t.Run("WithAddTagsMultiple", func(t *testing.T) {
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:skipped",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_name_length",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_tags",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_tag_length",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(1), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:flushed",
+			"veneurglobalonly:true",
+		}, 1.0)
+
+		server.Workers[0].PacketChan <- samplers.UDPMetric{
+			MetricKey: samplers.MetricKey{
+				Name: "test.metric",
+				Type: "counter",
+			},
+			Digest:     0,
+			Scope:      samplers.LocalOnly,
+			Tags:       []string{"anotha:thing", "foo:baz", "more:tags"},
+			Value:      1.0,
+			SampleRate: 1.0,
+		}
+
+		result := <-channel
+		if assert.Len(t, result, 1) {
+			assert.Equal(t, "test.metric", result[0].Name)
+			if assert.Len(t, result[0].Tags, 3) {
+				assert.Equal(t, "anotha:one", result[0].Tags[0])
+				assert.Equal(t, "foo:bar", result[0].Tags[1])
+			}
+		}
+	})
+
+	t.Run("WithAddTagsDoesNotMax", func(t *testing.T) {
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:skipped",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_name_length",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_tags",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_tag_length",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(1), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:flushed",
+			"veneurglobalonly:true",
+		}, 1.0)
+
+		server.Workers[0].PacketChan <- samplers.UDPMetric{
+			MetricKey: samplers.MetricKey{
+				Name: "test.metric",
+				Type: "counter",
+			},
+			Digest:     0,
+			Scope:      samplers.LocalOnly,
+			Tags:       []string{"anotha:thing", "foo:baz", "more:tags", "tags:fordays", "last:one"},
+			Value:      1.0,
+			SampleRate: 1.0,
+		}
+
+		result := <-channel
+		if assert.Len(t, result, 1) {
+			assert.Equal(t, "test.metric", result[0].Name)
+			if assert.Len(t, result[0].Tags, 5) {
+				assert.Equal(t, "anotha:one", result[0].Tags[0])
+				assert.Equal(t, "foo:bar", result[0].Tags[1])
+				assert.Equal(t, "more:tags", result[0].Tags[2])
+				assert.Equal(t, "tags:fordays", result[0].Tags[3])
+				assert.Equal(t, "last:one", result[0].Tags[4])
+			}
+		}
+	})
+
+	t.Run("WithAddTagsHitsMaxTags", func(t *testing.T) {
+		mockStatsd.EXPECT().Count("dropped_metrics", int64(1), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"metric_name:test.metric",
+			"reason:max_tags",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:skipped",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_name_length",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(1), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_tags",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:max_tag_length",
+			"veneurglobalonly:true",
+		}, 1.0)
+		mockStatsd.EXPECT().Count("flushed_metrics", int64(0), []string{
+			"sink_name:channel",
+			"sink_kind:channel",
+			"status:flushed",
+			"veneurglobalonly:true",
+		}, 1.0)
+
+		server.Workers[0].PacketChan <- samplers.UDPMetric{
+			MetricKey: samplers.MetricKey{
+				Name: "test.metric",
+				Type: "counter",
+			},
+			Digest:     0,
+			Scope:      samplers.LocalOnly,
+			Tags:       []string{"anotha:thing", "foo:baz", "more:tags", "tags:fordays", "last:one", "max:tags"},
+			Value:      1.0,
+			SampleRate: 1.0,
+		}
+
+		result := <-channel
+		assert.Len(t, result, 0)
+	})
+}
+
 type anyOfMatcher struct {
 	s []string
 }