error if one use fckeditor module

if one click on Administer>Formbuilder voice menu (the url: admin/formbuilder)

Fatal error: Cannot redeclare fckeditor_iscompatiblebrowser() (previously declared in
..sites/all/modules/fckeditor/fckeditor/fckeditor.php:36)
in
..sites/all/modules/fckeditor/fckeditor/fckeditor.php on line 34

this is fckeditor.php:
row 34 function FCKeditor_IsCompatibleBrowser()
{
row 36 if ( isset( $_SERVER ) ) {
$sAgent = $_SERVER['HTTP_USER_AGENT