So i wanna gift a friend a champ - the problem is i don't know what champs they currently own already. For example I already gifted them nidalee, I then almost accidently gifted nidalee again to the same person as there is no way to know what champs they already own unless you've seen them play it in their match history.
So I suggest that Riot makes it so that friends can see the champions other friends own when viewing their profiles
Not showing you your friend's entire inventory was a tough decision we made knowing that it would cause friction. That said, we've done our best to make sure that you can't gift things your friend can't use in the best ways possible.
No worries about being charged for gifting something they already own.