Hustle and Constant Contact issue

I've connected Hustle with my Constant Contact. I've directed that emails be saved to a contact list, let's call it LIST1. But when someone who is already in my MAIN Constant Contact list subscribes to get the download, they are blocked from doing so because it states they are already subscribed.
But they are not subscribed to the LIST1, but my MAIN list. If I use the proprietary Constant Contact plugin, when people subscribe to download, even if they are in my MAIN contacts they are still able to subscribe because they are not in LIST1.
Is there a way to solve this?