1. "Safe & Sound" (Season 1, Episode 19): Sung by Lea Michele (Rachel Berry) and Mark Salling (Noah "Puck" Puckerman).
2. "Mine" (Season 2, Episode 2): Performed by Chris Colfer (Kurt Hummel) and Naya Rivera (Santana Lopez).
3. "Mean" (Season 2, Episode 11): Sung by Darren Criss (Blaine Anderson) and Lea Michele (Rachel Berry).
4. "I Knew You Were Trouble" (Season 3, Episode 12): Performed by Chris Colfer (Kurt Hummel), Kevin McHale (Artie Abrams), Amber Riley (Mercedes Jones), and Naya Rivera (Santana Lopez).
5. "We Are Never Ever Getting Back Together" (Season 4, Episode 3): Sung by Lea Michele (Rachel Berry) and Cory Monteith (Finn Hudson).
6. "Shake It Off" (Season 5, Episode 14): Performed by Lea Michele (Rachel Berry) and Melissa Benoist (Marley Rose).
It's important to note that this list is not exhaustive, and there may be other Taylor Swift covers that were performed on "Glee" that are not mentioned here.