Well, this is true. The problem comes from when DC has tried to smash three different hells together in the same universe (Like when they rolled Trigon and The Triumvirate together). From what I recall, Constantine has never actually met Vertigo Lucifer in the canon comics; his dealings have always been with The Triumvirate Lucifer, whereas Vertigo Lucifer always ruled alone (again, as far as I remember). That brings another point, though. As far as I can tell, Full Power Vertigo Lucifer is far, far more powerful than any other version of Lucifer that has ever been shown to exist in the wider DC Multiverse, so there needs to be a justification there as to why that is. If we go with the idea that The Vertigo-verse was the "First" DC Universe, that answers that rather nicely. Lucifer, being the first Lucifer, was super powerful. Then, as they created new universes, the subsequent Lucifers were weaker to avoid such a devastating war happening again? I dunno. I'm rambling now. xD<br/><br/>OK. NEW IDEA.<br/><br/>In this Canon, there are several different "Hell Dimensions" that transcend the Parallel Universes (Earth-1, Prime Earth, New Earth, etc). So, you have the Hellblazer Hell that is run by Beelzebub, Azazel and...fuck, I dunno, Neron. You have another "Hell" that is run by the celestial conqueror Trigon, and you have the Vertigo Hell, which was ruled by Lucifer. Similarly, you have a few different versions of Heaven. Each of these have their own rules and hierarchies, but there's only one instance of them across the multiverse, so you have ONE Lucifer, ONE Trigon, ONE Neron, ONE Ertigan, etc etc.<br/>That could help clear up the cosmology, and add room for others being added in later, like - for example - the Hellboy Hell.