Add backup Librem Key to L14 before or after?

I can use the smartcard-key-luks shell script to add a Librem Key to my Librem 14 boot process. If I already have a primary Librem Key enabled in my boot process and I run this script with a new backup Librem Key, does it augment or replace the primary Librem Key?

(I have simplified my quest into a simple binary question. A simple one word response with “augment” or “replace” will suffice.)