If I have two plugins installed that both use CMB2 for their options/fields I see: Fatal error: Cannot redeclare cmb2_dir() (previously declared in /srv/www/wordpress-default/wp-content/plugins/.../includes/libraries/cmb2/includes/helper-functions.php:18) in /srv/www/wordpress-default/wp-content/plugins/.../includes/libraries/metabox/includes/helper-functions.php on line 18

I see that it's simply required here: https://github.com/WebDevStudios/CMB2/blob/master/init.php#L144

Shouldn't these functions be wrapped in a function_exists() conditional? How can multiple plugins/themes use CMB2 successfully with the helper functions included like this?