Fix CustomCommandListener

Signed-off-by: yoyosource <yoyosource@nidido.de>

BauSystem_Main/src/de/steamwar/bausystem/features/script/CustomCommandListener.java

@@ -267,6 +267,15 @@ public class CustomCommandListener implements Listener {
                 return;
             }
             MenuCommand menuCommand = new MenuCommand(bookMeta.getPages(), s.substring(6).split(" "));
+            for (CustomCommand customCommand : playerMap.computeIfAbsent(p, player -> new ArrayList<>())) {
+                if (!(customCommand instanceof MenuCommand)) {
+                    continue;
+                }
+                if (Arrays.equals(((MenuCommand) customCommand).args, menuCommand.args)) {
+                    p.sendMessage("§cCommand '" + (String.join(" ", menuCommand.args)) + "' bereits definiert");
+                    return;
+                }
+            }
             playerMap.computeIfAbsent(p, player -> new ArrayList<>()).add(menuCommand);
             if (!save(p)) {
                 playerMap.get(p).removeIf(customCommand -> customCommand == menuCommand);