Inconsolable (Backstreet Boys) / Little Things (One Direction)
Bye Bye Bye (*NSYNC) / I Want It That Way (Backstreet Boys)
Quit Playing Games (With My Heart) [Backstreet Boys] / Tearin’ Up My Heart (*NSYNC)
REMEMBER: Only one of these is correct. We’ll say which one, and who’s singing, tomorrow!
It is probably the 2nd choice based on this tweet (click for source)
in reference to the "Bye Bye Bye" video: