how can i successfully installing a mpdf and phpmailure package in laravel using mpdf/mpdf and phpmailure/phpmailure?

I have a problem in laravel during installing mpdf and phpmailure packages....

Fatal Error: Cannot redeclare redirect() (previously declared in F:\www\htdocs\SCER-back-end\vendor\laravel\framework\src\Illuminate\Foundation\helpers.php:543) in F:\www\htdocs\SCER-back-end\vendor\symphonycms\symphony-2\symphony\lib\boot\func.utilities.php on line 41

via Chebli Mohamed