Why can a method in a native module fire twice?

Question

1C-Bitrix

Good day!
I started to cut my first module and immediately ran into the following problem:
When installing, I attach a function to the onAfterEpilog event

RegisterModuleDependences("main", "OnAfterEpilog", "modulname", "cMainClass", "AfterEpilog");

In the AfterEpilog function, I draw some kind of conclusion, it doesn’t matter.

class cMainClass {
  static $MODULE_ID = "modulname";

  function AfterEpilog(){
     echo "true";
  }
}

I include the class in include.php.

<?php
CModule::IncludeModule("modulname");
global $DBType;
$arClasses = array(
    'cMainClass '=>'classes/general/cMainClass .php'
);
CModule::AddAutoloadClasses("modulname", $arClasses);

And as a result, the result of the AfterEpilog function is returned twice: truetrue.
Where could be the problem?