Once you start building your deck, you will likely have duplicate cards in your collection. You are welcome to keep them but players now have the option to convert these duplicates for Mana Runes. To convert these duplicates, please head to the Inventory, and click on the green button at the top labeled "Convert Duplicates".
At this time, all duplicate cards will then be converted into Mana Runes. A Common card, is worth 20 runes, a Uncommon card is worth 40 runes, a Rare card is worth 200 runes, a Mythic card is worth 1000 runes and a Masterpiece card is worth 5000 runes.
Please Note: Booster Crafting is coming in late June that will change the way duplicate cards are handled in MTGPQ - See details HERE.