Constant QLWCDC_PLUGIN_NAME already defined

I Installed this Plugin, and It is not Compatible with Direct Checkout Pro. I Think It only needs to change one Variable throughout the Plugin Files. I can get it done in Backend on my own, but then firstly will need to check all files for the Constant. And Secondly all changes will be Wiped after Update.

Hence Notifying the Developers. Please Get it Rectified. Following is the Error Message I am getting.

Constant QLWCDC_PLUGIN_NAME already defined in /home/my.webhosting.com/randomfolder/public_html/wp-content/plugins/woocommerce-direct-checkout/woocommerce-direct-checkout.php on line 19

Thanks for this Lovely Plugin. Hoping to get this Fixed ASAP.