Brett Ratner Kissing NOT Mariah Carey (PHOTOS)

Hmmmm ...

Don't know what to say about this. Brett Ratner making out with a chick on the same yacht where he was nuzzling Mariah Carey.

People on the boat said Brett and Mariah were in full-on couple mode, and we're told both of them loved our posts over the weekend.

But check this out ... Brett on the same yacht Sunday night in the Caribbean, sucking face with another chick.