There were a bunch of sessions back in the day that had both Jim Keltner and Ringo playing drums. A few guys who've doubled up with Keltner said he has the ability to melt into what was going on without it being noticed he was there until you muted his tracks. Not a surprise from him. For lack of a better term, he's on a different "metaphysical" level from most of us where the drums are concerned IMO. "The Concert For George" is a good opportunity to watch him in his 2nd drummer role.
Also, "Hey Nineteen" by Steely Dan has both Gadd and Rick Marotta rounding out that track so tastefully that it sounds like one guy, along with "Glamour Profession" on Gaucho.
I did some stuff in Nashville with a second drummer and I tell ya, if you and the other guy are listening and "Gets it", it's like you're the crew on an B-17 or something. Feels like driving a steamroller. Big ol' fun.
ETA- At one point, James Brown had !FIVE! drummers onstage BUT according to Jabbo, there were never 2 drummers playing time simultaneously.