diff --git a/benchmark-proxy/main.go b/benchmark-proxy/main.go
index a377583c..30f2bbbe 100644
--- a/benchmark-proxy/main.go
+++ b/benchmark-proxy/main.go
@@ -492,12 +492,33 @@ func handleWebSocketRequest(w http.ResponseWriter, r *http.Request, backends []B
 			backendURL := strings.Replace(b.URL, "http://", "ws://", 1)
 			backendURL = strings.Replace(backendURL, "https://", "wss://", 1)
 
-			// Copy headers for the dialer
+			// Create a clean header map for the dialer
+			// Instead of copying all headers which can cause duplicates
 			header := http.Header{}
-			for name, values := range r.Header {
-				for _, value := range values {
-					header.Add(name, value)
-				}
+
+			// Only copy specific headers needed for the WebSocket connection
+			// and avoid the problematic ones like "Connection" and "Upgrade"
+			if host := r.Header.Get("Host"); host != "" {
+				header.Set("Host", host)
+			}
+			if origin := r.Header.Get("Origin"); origin != "" {
+				header.Set("Origin", origin)
+			}
+			if secWebSocketKey := r.Header.Get("Sec-WebSocket-Key"); secWebSocketKey != "" {
+				header.Set("Sec-WebSocket-Key", secWebSocketKey)
+			}
+			if secWebSocketVersion := r.Header.Get("Sec-WebSocket-Version"); secWebSocketVersion != "" {
+				header.Set("Sec-WebSocket-Version", secWebSocketVersion)
+			}
+			if secWebSocketProtocol := r.Header.Get("Sec-WebSocket-Protocol"); secWebSocketProtocol != "" {
+				header.Set("Sec-WebSocket-Protocol", secWebSocketProtocol)
+			}
+			if secWebSocketExtensions := r.Header.Get("Sec-WebSocket-Extensions"); secWebSocketExtensions != "" {
+				header.Set("Sec-WebSocket-Extensions", secWebSocketExtensions)
+			}
+			// Add user-agent if present
+			if userAgent := r.Header.Get("User-Agent"); userAgent != "" {
+				header.Set("User-Agent", userAgent)
 			}
 
 			startTime := time.Now()