diff --git a/jupyter/stock.py b/jupyter/stock.py
index 9f5aeaf..9d0ac65 100644
--- a/jupyter/stock.py
+++ b/jupyter/stock.py
@@ -771,7 +771,8 @@ class WebServer:
             if not session_id in self.sessions:
                 self.generate_session(ws, session_id)
 
-            self.sessions[session_id]['sockets'].append(ws)
+            if ws not in self.sessions[session_id]['sockets']:
+                self.sessions[session_id]['sockets'].append(ws)
 
             while True:
                 try:
@@ -837,6 +838,7 @@ class WebServer:
                         self.sessions[session_id]['sockets'].remove(ws)
                     for socket in self.sessions[session_id]['sockets']:
                         socket.send(json.dumps({"type": "users", "update": self.sessions[session_id]['users']}))
+                    return
 
         # Serve React app - This catches all routes not matched by API endpoints
         @self.app.route('/')