Lamar Odom -- Club Was Afraid He'd Start a Brawl ... Chris Brown & Drake Style

The plot thickens -- the nightclub Lamar Odom got denied from insists the rejection was NOT a reality show set-up ... Lamar was turned away because the club was afraid he'd start a Chris Brown-level brawl with French Montana.

As we reported, Odom was spurned from Penthouse in West Hollywood while his ex Khloe Kardashian and her new man French Montana partied inside.

An E! camera crew was conveniently posted up outside the club to capture the rejection -- so obviously there was speculation that Lamar's rejection was a set-up for "Keeping Up with the Kardashians" -- but a rep for Penthouse tells TMZ, not so.

The rep says the decision to deny Lamar was the club's decision alone. We're told the nightclub wanted to avoid another bottle-throwing Chris Brown-Drake situation, so bouncers refused to let him in.

Sources close to the Kardashians tell us the same story -- Khloe didn't even know Lamar planned to show up.

You'll recall, Brown and Drake were involved in a massive brawl at W.i.P. nightclub in NYC back in 2012. The brawl resulted in a bunch of lawsuits ... and the club even lost its liquor license for a while. So it's no wonder Penthouse was playing it safe.

9:44 A.M. PDT -- Khloe just tweeted this: "Still hurts... Maybe it always will"