the first time you cast mockingjay when you chose to pay any amount of mana for the spell, you get one less mana to help copy a creature. the first mockingjay you cast if you pay (1) mana to play the spell, you should get to copya creature that costs up to (2) total. It doesn't. It only behaves appropriately after you've played the spell or attempted to play the spell and then canceled the spell and tried again. After that, the spell works correctly for any other copies you play.