Buying Guaranteed Non-Duplicates and Exclusives

I find myself avoiding any of the supposedly guaranteed non-duplicate sets of cards if I already purchased exclusive art versions of the cards that I don't have in the regular version. The thought of coughing up all those crystals only to get the regular version of a card I already own when it's supposed to be non-duplicate kind of makes me ill.

I would like to suggest adding a checkbox or similar to the purchase page of a guaranteed non-duplicate set that allows you to be guaranteed (the whole point of paying extra, after all) to not get a card that you already own in another form. That way people can choose whether or not they want multiple versions, or if they're only getting the cards for their abilities and not for their art.