WooCommerce Subscriptions Renewals triggers list addition

I’m running this plugin on a site that sells subscription products via the WooCommerce Subscriptions plugin. It works fine, with one hiccup — Everytime a subscription renews (each month in my case), it tries to add the user to the Mailchimp list. It won’t if they’re already there, as you’d expect, but it seems as if only the first, initial order of a subscription should trigger the Mailchimp push.

Any thoughts on how to tweak this behavior for subscription products?