Error redeclare class

Hello
I make library Message.php and auto load it in config/autoload.php
I use it in one of models
But it get error below when i use it
( ! ) Fatal error: Cannot redeclare SendEmailMessage() (previously declared in C:\wamp64\www\alis.ir\Alis_WebService\application\libraries\Message.php:56) in C:\wamp64\www\alis.ir\Alis_WebService\application\libraries\Message.php on line 56

I cannot find where is redeclare class?