Revealed Cards | Discarding Unrevealed Duplicate
When having multiple copies of a card in hand (one or more of which are revealed and one or more of which are not revealed), discarding any copy of that card (including an unrevealed copy) removes one of the revealed copies.
It should be up to the player to choose whether or not they want to discard a revealed card or an unrevealed duplicate (when given a choice of which to discard), as there are reasons a player may choose to discard an unrevealed duplicate of a card and keep the revealed card in their hand. It should not be a forced system of removing revealed cards regardless of which one is actually discarded. More so when the player does not get a choice of which to discard.
Example, which happened in a game - I used Perilous Iteration and one of the cards it pulled was a Stormfist Crusader, which was unrevealed. I used the Incubation side of Incubation//Incongruity and the only creature it gave was a second Stormfist Crusader, which was revealed to the opponent. I played neither, and at the end of the second turn Perilous Iteration discarded its unrevealed copy and the revealed one from Incubation stopped being revealed.
Either way this specific interaction is handled the opponent would know I had two copies of the same card in hand. However, technically, the one that was force-discarded was not the one that was revealed and sort of violates Arena's own system of keeping revealed cards revealed.