Younes Bendjima double-crossed Kourtney Kardashian by tipping off the paparazzi that she was having a secret meeting with him in a Malibu parking lot ... sources close tell TMZ.

We're told Kim and Khloe have solid reasons to believe the secret rendezvous photo -- obtained by TMZ -- was staged by Younes to squeeze out the last drops of his 15 minutes. 

We broke the story ... Kourtney was in the passenger seat of her Range Rover outside of a Malibu sushi joint Monday night, sparking rumors they were back together. Sources close to the exes quickly let us know that wasn't the case -- their chat was all about closure.

We're told Younes made the call to drive to that sushi spot -- a place the 2 had never been -- to park and have a talk. So, it seems awfully suspicious to the sisters that a photog was on scene.

Our sources say the Kardashians believe Younes frequently tipped off paps while he dated Kourt ... because they would show up at random places where the 2 were hanging out, and there's no way they would have known in advance.

We're told the sisters think Younes knew his relationship with Kourtney was over ... and this was his Hail Mary for the last bit of publicity.

Our sources also say ... the girls are more than happy Kourtney has moved on.