I don't know what "true" means. I'd say maybe hold them at once and defend them at the same time. Behind that win one, defend it a bunch, move up and win another defend that one too. Anything else just screams of oppurtunism. Part of what makes the "champ champ" path to greatness so dumb to me is that while title defense records and win records and the like require time, this is a title that can be done by anyone if the UFC lets them and the champions at other divisions aren't the same sort of challenge. So in one fight you get to be "champ champ". Then if a fighter moves division for the right reasons they probably lost in the old division. So it's a lose lose.
The way it is now
1 normal defense=average champion
1 "superfight"=legend or something?
Couture and Penn both became double division champs because they lost at the division they originally competed at. Couture lost at the division he competed at went to LHW was dethroned there and went back to HW again. Penn lost at WW moved to LW then lost a "superfight" to a WW.
GSP retired after the Hendricks "win" and went to MW when he saw a MW champ he knew he could beat, then ran away again. After the Serra fight this is the most risk adverse athlete I've ever seen except maybe Floyd.
Conor won his first title never defended, got a shot at second title after losing beating an irrelevant big mouth at the division and got it. Guys never defended a belt. Didn't get moved down the ladder for losing to Diaz but got a title shot for beating him. Sure that would have happened to anyone.
DC got his first belt because a guy he lost to got in trouble and got the shot coming off a loss. Guy took his belt from him again and because he pissed hot in an ongoing PED case he was given the belt back. Second belt he got a shot right away because he earned this first belt. Also bounced once this fighter returned.
Nunes won belt one defended three times then won belt two against Cyborg.
IMO Nunes is the only one who I'd call a true two division champ and is three defenses really a lot before going up? The rest either were put in that position cause they couldn't win at another division(BJ Penn it's even more clear cause he lost at WW, won at LW then lost again to GSP) because they engineered it or because they got a shot and belt they didn't deserve. It says almost nothing positive IMO.