When Cheech & Chong was mention, I thought of The Smothers Brothers. And possibly Abbott and Costello. All "old-school."I was thinking Smothers Brothers. And Burns and Allen
I wonder if duos are more associated with film/radio/TV/sketch comedy than stand-up, although C&C started as on-stage and they've still had some recently in that format.
Key & Peele would be a modern one, but it's closer to the form of Monty Python / The Kids in the Hall / In Living Color
Garfunkel and Oates is a current one that seems more stand-up oriented.