How do I permanently get rid of duplicate treasure cards?

[1970zombie]

How do I permanently get rid of duplicate treasure cards? You used to be able to do this from the collection screen where you received gold for removing the card. The merchant now gives you gold for some cards that you banish but they still remain a part of your collection.

 

I am looking to reduce the probability of seeing certain cards because I have 5 or more copies in the available pool.