The cloning card says you play an attack from your played cards and then again if it's in your discard....
How is it possible to have the same card in both the played and discard pile when there is only one copy of each card? Am I reading this card wrong?
The card states:
Reveal a non-Throughout and non-Enchancement card in your discard pile and play it. Then play it again if it is in your played pile.
The card first asks you to find a card in your discard pile and play it. The last step of "playing cards" is to put the card in your played pile. Then, we go to the next step where if this card if in your played pile (which it now is), you may play it again.
Now naturally, this would almost always occur. However, there are rare exception such as Shadow Cloning the card "Eternal Migrant" or "Glancing Strike", where after the attack the card gets put back in the deck after the attack and thus is no longer in your played pile.