American Idol Secret?

Okay, when I was watch AI last night, when LaKisha (however you spell it) performed, the ending of her song sounded awful, but in the recaps, it sounded a lot better. It sounded completely different! I'm beginning to think it was two seperate performances. I've noticed it before in previous episodes in different seasons, but I thought it was my imagination. Is it something that everyone knows about except me? Tell me if the original performance and the recaps are different performances. Thanks!