NOT on purpose:
1. Sean Gunn appeared as both Kirk Gleason — a quirky Stars Hollow townsfellow — and Mick — a maintenance repair man — in Gilmore Girls:
2. Alex Borstein appeared as both Drella — a sassy harpist — and Miss Celine — Emily's annoying stylist — in Gilmore Girls:
3. Pablo Schreiber appeared as both William Lewis — a deranged killer obsessed with Benson — and Dan Kozlowski — the father of a victim — in Law & Order: Special Victims Unit:
4. Mouzam Makkar appeared as both Raina Punjabi — a video game developer who gets attacked by incels — and Dara Miglani — a defense attorney — in Law & Order: Special Victims Unit:
5. Hayden Panettiere appeared as Ashley Black — a neglected child who develops a close bond with Benson — and Angela Agnelli — a school girl with a double life — in Law and Order: Special Victims Unit:
6. Dean-Charles Chapman appeared as King Tommen — Cersei and Jaime's second son — and Martyn Lannister — a murdered squire — in Game of Thrones:
7. Justin Theroux appeared as both Jared — a self-absorbed writer — and Vaughn Wysel — a boyfriend of Carrie's whose family she liked more than him — in Sex and the City:
8. Garret Dillahunt appeared as both Jack McCall — the drunk murderer of Bill Hickok — and Francis Wolcott — a geologist for the Hearst empire — in Deadwood:
9. Keegan Connor Tracy appeared as both Sera Siege — a book publisher — and Witch Mother — Jacinda and Emily's mom — in Supernatural:
10. Queen Latifah appeared as both Hilary's annoying boss and Marissa — Will's love interest — in The Fresh Prince of Bel-Air:
11. Michelle Williams appeared as two different one-off characters in Baywatch:
TOTES on purpose:
12. Tobias Menzies appeared as both Frank Randall — Claire's husband in present day — and Black Jack Randall — Frank's ancestor who assaults and harasses Claire and Jamie in the past — in Outlander:
13. D'Arcy Carden appeared as several iterations of Janet as well as other characters in The Good Place:

14. Donald Glover appeared as both Earn Marks — Paper Boi's cousin and manager who's prone to making bad decisions — and Teddy Perkins — a creepy and mysterious recluse — in Atlanta:
15. Evan Peters appeared as various characters in American Horror Story:
16. Sarah Paulson appeared as various characters in American Horror Story:
17. Jessica Lange appeared as various characters in American Horror Story:
18. Nina Dobrev appeared as both Elena Gilbert — a high school student torn between two vampires — and Katherine Pierce — Elena's evil doppelgänger — in The Vampire Diaries:
19. David Schwimmer appeared as both Ross — one of the core six — and Russ — Rachel's episode-long boyfriend — in Friends:
20. Jeffrey Wright appeared as Bernard Lowe — a host created by Dr. Ford and made in the image of the late Weber — and Arnold Weber — the late co-founder of Westworld — in Westworld:
21. Sheryl Lee appeared as Laura Palmer — a murdered teen girl who led a double life — and Maddy Ferguson — Laura's cousin who comes to the town to help comfort her aunt and uncle — in Twin Peaks:
22. Last, but not least, Tatiana Maslany appeared as almost everyone in Orphan Black:
