Kylie and Kendall Jenner -- Hung Out with Nightclub Promoter Before Underage Partying

Kylie and Kendall Jenner rolled into Vignette Lounge like V.I.P.s -- hanging with the club promoter ... which punches a big hole in claims the staff was clueless about who they were when they arrived.

TMZ obtained pics of Darren Dzienciol hanging with Scott Disick and K&K at a fashion show earlierTuesday night. Darren works with Bartelier Group which promotes parties all over L.A. -- including the 21-and-over Wax Rabbit event at Vignette that very night.

As we reported, Vignette's manager claims the underage Jenner girls showed fake IDs when they entered the club Tuesday night ... and that bouncers didn't recognize they were Kardashians.

Darren was also one of the guys ushering Kylie and Kendall out of the club underneath blankets -- most likely to hide their identities ... and possibly because they were tipsy.

So, even if the club's staff didn't know the girls were minors -- which seems extremely unlikely -- the club's head promoter that night certainly did.