Error with WC mini cart block

When a “woocommerce/mini-cart” block is in the header, there is a warning on pages using the “rent-add-to-cart” shortcode.

Warning: Constant add_to_cart_id already defined in?\wp-content\plugins\booking-and-rental-manager-for-woocommerce\inc\rbfw_shortcodes.php?on line?178

This error doesn’t exist if I remove either the cart or the shortcode.

Any assistance with this would be appreciated.

Thanks!