It happens in Gilmore Girls World from time time. An actor appears on the show as one character and then reappears, in later episodes, as another!
Floyd Van Buskirk made his Gilmore Girls debut in season 1, episode 5 as Jed, and then again in season 5, episode 2, “A Messenger, Nothing More,” as Henry, who is apart of the Renaissance Fair.

Gilmore Girls Gazette: Is that Jon Hamm’s real butt, one of Matt Czuchry’s co-stars is joining Paradise
22:30

IAAI Town Meeting: Lorelai and Rory Do Something That Makes Us Question Their Sanity (Season 4 E1 “Ballrooms and Biscotti”)
31:42

I Am All In Again…Something people think is nerdy that Rory made cool! (Season 4 E1 “Ballrooms and Biscotti”)
28:36