No, I'm referring to the ones on the Star Forge DP pictured above.
Unless DP can confirm otherwise, that is absolutely not the case... DP's mod replaces the appearances of the 3 Sith Masters on the Star Forge though my mod uses them on Tatooine and Kashyyyk assuming you wouldn't use DPs mod.
That means if you use Dark Jedi Wear Robes & NPC Diversity Pack you could get the exact same Dark Jedi you see in DP's above screenshot.
If you don't mind that, then yes you can play both mods just fine assuming you install Dark Jedi Wear Robes after the NPC Diversity Pack, but if not I will say this: the use of the Star Forge Sith Masters on generic Dark Jedi does not have to be a permanent feature of the NPC Diversity Pack.
The Czerka greeter on Tatooine who you pay to enter Tatooine and the Czerka Merchant on Korriban both use the Czerka Commander appearance, but that's not permanent as I intend to eventually make a Czerka themed mod to replace those guys & give them unique appearances... right now I'm developing the Mandalorian themed mod.
Eventually, I'll make my own Dark Jedi themed mod which would do the same thing as Hearts of Beskar which would add new Dark Jedi variants to the game. I'm not sure if this mod would be compatible with DP's Dark Jedi Wear Robes as my mod would be very uniformed meaning, for example, Sith Assassins have a distinct look, Dark Jedi have a distinct look, Sith Lords have a distinct look... whereas Dark Jedi Wear Robes doesn't have anything like that, in-fact, it looks as if males have Sith Lord mask whilst females have a Sith Assassin mask. What I'm saying is, it might not look good alongside my highly uniformed work.
But for now, if requested, I might consider replace the generic Dark Jedi who use Star Forge Master appearances to ensure compatibility between the two mods.