Ellie Goulding (with Andra Day)
Carrie Underwood (with Sam Hunt)
Tori Kelly (with James Bay)
Pitbull (with Robin Thicke and Travis Barker)
Chris Stapleton (with Gary Clark Jr. & Bonnie Raitt – B.B. King tribute)
Well, that's five. Unless the BB King tribute doesn't count as a "duet." The Lionel Richie tribute might be the sixth.
There's no tribute to the man from The Eagles?