Not only did Michael do duets during the 80's, he also was part of the "let's all get together and record large ensemble pieces for charity" movement.

(This isn't dissing what they did, but my goodness there were a lot of noun-aid concerts during the 80's)

Here's Michael's contribution, co-written by Lionel Richie and sung by a heck of a lot of people -- "We Are the World"...