There is only one case when someone beat best fighter in division to become one, and it was DC, at this moment it clearly doesn’t say much and fighter only challenges for double champ status when there is favourable matchup waiting, GSP never would’ve fought Romero, Rockhold or Conor Khabib if those guys were champs, so for me it is unnecessary division messing and doesn’t prove anything if you just jump at occasion to get that shit, and also, Aldo would’ve been double champ 100%, but ufc didn’t allow that shit back in day