Gamestop buy 2 gamecube games get 2 free

So i was looking to buy some gamecube games online at gamestop and i noticed there's a deal in the trade in section that says "Buy 2 gamecube games get 2 free" is this valid online, because there's no code instruction to enter in checkout/mention of its online use

It should be automatic. I just added 4 copies of Super Mario Sunshine to my cart at 24.99 apiece, and it's only charging me for two of them.

I this still valid? And if so, is it also in store?