Index: head-src/com/l2jfrozen/gameserver/thread/LoginServerThread.java
===================================================================
--- head-src/com/l2jfrozen/gameserver/thread/LoginServerThread.java    (revision 1004)
+++ head-src/com/l2jfrozen/gameserver/thread/LoginServerThread.java    (working copy)
@@ -507,9 +507,19 @@
         pl = null;
     }

-    public void addGameServerLogin(String account, L2GameClient client)
-    {
-        _accountsInGameServer.put(account, client);
+        /*
+
+         * @return {@code true} if account was not already logged in, {@code false}
+
+         * otherwise
+
+         */
+
+        public boolean addGameServerLogin(String account, L2GameClient client) {
+
+            return ((FastMap<String, L2GameClient>) _accountsInGameServer).putIfAbsent(account, client) == null;
+
+
     }

     public void sendAccessLevel(String account, int level)