Best I know of is Sharon Horgan's actually-really-good Pulling, which has:
Paul Kaye (Thoros of Myr/Billy)
Josef Altin (Pypar/Skinzo)
Tom Brooke (Lothar Frey/Greg)
Tobias Menzies (Edmure Tully/Stefan)
Maybe more but probably not.
Guess we can do films and film series too, so Harry Potter has the most I can think of:
Michelle Fairley (Catelyn Stark/Mrs. Granger)
Natalia Tena (Osha/Nymphadora Tonks)
David Bradley (Walder Frey/Argus Filch)
There's probably more harry potter, idk, I'm a 29 year old man.