diff --git a/cmd/publish.go b/cmd/publish.go
index 34ea667..73ca564 100644
--- a/cmd/publish.go
+++ b/cmd/publish.go
@@ -27,6 +27,7 @@ var (
 	//optional
 	serviceURL string
 	useGRPCPub bool // gRPC flag for publish
+	noDedup    bool // Flag to disable deduplication (no timestamp)
 )
 
 // PublishPayload matches the expected JSON body on the server
@@ -34,7 +35,7 @@ type PublishRequest struct {
 	ClientID  string `json:"client_id"`
 	Topic     string `json:"topic"`
 	Message   string `json:"message"`
-	Timestamp int64  `json:"timestamp"`
+	Timestamp *int64 `json:"timestamp,omitempty"` // Optional timestamp for duplicate detection
 }
 
 // addDebugPrefix adds debug information prefix to message data
@@ -194,11 +195,22 @@ var publishCmd = &cobra.Command{
 				publishData = addDebugPrefix(data, proxyAddr)
 			}
 
+			var timestamp *int64
+			if noDedup {
+				// When --no-dedup is set, omit timestamp so proxy uses MsgHash(topic, message)
+				// instead of MsgHashWithTimestamp. This allows same message to be sent once per session
+				timestamp = nil
+			} else {
+				// Default: include timestamp so proxy uses MsgHashWithTimestamp
+				ts := time.Now().UnixMilli()
+				timestamp = &ts
+			}
+
 			reqData := PublishRequest{
 				ClientID:  clientIDToUse,
 				Topic:     pubTopic,
 				Message:   string(publishData), // use modified data with debug prefix if enabled
-				Timestamp: time.Now().UnixMilli(),
+				Timestamp: timestamp,
 			}
 			reqBytes, err := json.Marshal(reqData)
 			if err != nil {
@@ -251,6 +263,7 @@ func init() {
 	publishCmd.Flags().StringVar(&file, "file", "", "Path of the file to publish (max 10MB)")
 	publishCmd.Flags().StringVar(&serviceURL, "service-url", "", "Override the default service URL")
 	publishCmd.Flags().BoolVar(&useGRPCPub, "grpc", false, "Use gRPC for publishing instead of HTTP")
+	publishCmd.Flags().BoolVar(&noDedup, "no-dedup", false, "Omit timestamp to use MsgHash(topic, message) instead of MsgHashWithTimestamp. Allows same message to be sent once per session (useful for stress testing/benchmarking)")
 	publishCmd.MarkFlagRequired("topic") //nolint:errcheck
 	rootCmd.AddCommand(publishCmd)
 }
diff --git a/e2e/publish_test.go b/e2e/publish_test.go
index bd84f32..a2a74e5 100644
--- a/e2e/publish_test.go
+++ b/e2e/publish_test.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"os"
 	"os/exec"
@@ -163,6 +164,99 @@ func TestPublishCommand(t *testing.T) {
 		require.Contains(t, strings.ToLower(out), "only one", "Expected error about using only one option")
 	})
 
+	// Test --no-dedup flag
+	t.Run("publish with --no-dedup=false (default, timestamp included)", func(t *testing.T) {
+		dedupTopic := fmt.Sprintf("%s-dedup-default", testTopic)
+		subCtx, subCancel := context.WithCancel(context.Background())
+		defer subCancel()
+
+		subCmd := exec.CommandContext(subCtx, cliBinaryPath, "subscribe", "--topic="+dedupTopic, "--service-url="+serviceURL)
+		subCmd.Env = os.Environ()
+		require.NoError(t, subCmd.Start(), "Failed to start subscriber")
+		time.Sleep(2 * time.Second)
+
+		// Publish same message twice - should get different message IDs (timestamp changes)
+		msg := "Test dedup message"
+		out1, err := RunCommand(cliBinaryPath, "publish",
+			"--topic="+dedupTopic,
+			"--message="+msg,
+			"--service-url="+serviceURL)
+		require.NoError(t, err, "First publish failed: %v\nOutput: %s", err, out1)
+
+		// Extract JSON response and verify status is "published"
+		var resp1 map[string]interface{}
+		jsonStart := strings.Index(out1, "{")
+		require.Greater(t, jsonStart, -1, "No JSON response found in output")
+		require.NoError(t, json.Unmarshal([]byte(out1[jsonStart:]), &resp1), "Failed to parse JSON response")
+		require.Equal(t, "published", resp1["status"], "First publish should have status 'published'")
+
+		// Small delay to ensure different timestamp
+		time.Sleep(100 * time.Millisecond)
+
+		out2, err := RunCommand(cliBinaryPath, "publish",
+			"--topic="+dedupTopic,
+			"--message="+msg,
+			"--service-url="+serviceURL)
+		require.NoError(t, err, "Second publish failed: %v\nOutput: %s", err, out2)
+
+		// Extract JSON response and verify status is "published" (different timestamp = different message ID)
+		var resp2 map[string]interface{}
+		jsonStart = strings.Index(out2, "{")
+		require.Greater(t, jsonStart, -1, "No JSON response found in output")
+		require.NoError(t, json.Unmarshal([]byte(out2[jsonStart:]), &resp2), "Failed to parse JSON response")
+		require.Equal(t, "published", resp2["status"], "Second publish should have status 'published' (different timestamp)")
+		require.NotEqual(t, resp1["message_id"], resp2["message_id"], "Message IDs should be different (different timestamps)")
+
+		subCancel()
+		subCmd.Wait()
+	})
+
+	t.Run("publish with --no-dedup=true (timestamp omitted)", func(t *testing.T) {
+		dedupTopic := fmt.Sprintf("%s-dedup-no-timestamp", testTopic)
+		subCtx, subCancel := context.WithCancel(context.Background())
+		defer subCancel()
+
+		subCmd := exec.CommandContext(subCtx, cliBinaryPath, "subscribe", "--topic="+dedupTopic, "--service-url="+serviceURL)
+		subCmd.Env = os.Environ()
+		require.NoError(t, subCmd.Start(), "Failed to start subscriber")
+		time.Sleep(2 * time.Second)
+
+		// Publish same message twice with --no-dedup - second should be deduplicated
+		msg := "Test no-dedup message"
+		out1, err := RunCommand(cliBinaryPath, "publish",
+			"--topic="+dedupTopic,
+			"--message="+msg,
+			"--no-dedup",
+			"--service-url="+serviceURL)
+		require.NoError(t, err, "First publish failed: %v\nOutput: %s", err, out1)
+
+		// Extract JSON response and verify status is "published"
+		var resp1 map[string]interface{}
+		jsonStart := strings.Index(out1, "{")
+		require.Greater(t, jsonStart, -1, "No JSON response found in output")
+		require.NoError(t, json.Unmarshal([]byte(out1[jsonStart:]), &resp1), "Failed to parse JSON response")
+		require.Equal(t, "published", resp1["status"], "First publish should have status 'published'")
+
+		// Publish same message again
+		out2, err := RunCommand(cliBinaryPath, "publish",
+			"--topic="+dedupTopic,
+			"--message="+msg,
+			"--no-dedup",
+			"--service-url="+serviceURL)
+		require.NoError(t, err, "Second publish should not error (deduplicated): %v\nOutput: %s", err, out2)
+
+		// Extract JSON response and verify status is "deduplicated" (same message hash without timestamp)
+		var resp2 map[string]interface{}
+		jsonStart = strings.Index(out2, "{")
+		require.Greater(t, jsonStart, -1, "No JSON response found in output")
+		require.NoError(t, json.Unmarshal([]byte(out2[jsonStart:]), &resp2), "Failed to parse JSON response")
+		require.Equal(t, "deduplicated", resp2["status"], "Second publish should have status 'deduplicated' when --no-dedup is used")
+		require.Equal(t, resp1["message_id"], resp2["message_id"], "Message IDs should be the same (no timestamp)")
+
+		subCancel()
+		subCmd.Wait()
+	})
+
 	// Cleanup: stop subscriber
 	cancel()
 	subCmd.Wait()