Thanks for this.
Just sharing some info to train same IV for 2pokemon with Macho Brace + Exp. Share:
Poke A will start with MB
Poke B will start with ES
Train untill A IV = 126, B will be 63. Now give Macho Brace to B and Exp Share to A, and battle with B of course. Now train untill B is 221, A will be 205 (they will get equal at 189 but that doesnt matter). Now switch itens again and train till A is 251, B will be 244, then finish.
The values will not always be exact, as sometimes you are 125 and go to 128... But this wont impact that much in the end, it is still the most optimal way for duo training.