Reduce status noise

urlchecker_bot.py

@@ -149,6 +149,7 @@ class WebBot:
                     continue
                 if server_ip not in server_ip_dict:
                     server_ip_dict[server_ip] = []
+                if dns_change["domain"] not in server_ip_dict[server_ip]:
                   server_ip_dict[server_ip].append(dns_change["domain"])
 
         # Report the list of CDN status