Gifting a key question

I already have a poe 2 key linked to my steam account. I want to buy a supporter pack which comes with another key, that I want to give to a friend. When i go to check out on steam it says " you will not receive another copy of path of exile 2 " is this the key I wont receive? Do i have to buy the pack elsewhere to be able to gift my friend the key?

Clarification would be appreciated.