Lindsay Lohan could be getting support from someone who has done cocaine waaaay more than 4 or 5 times ... 'cause Brooke Mueller's in the house!
Sources familiar with cocaine tell TMZ ... Brooke and Lindsay are currently staying in the hospital wing at The Betty Ford Center in Rancho Mirage. In fact we're told they've already run into each other and exchanged pleasantries ... not drugs.
The question -- who mentors who? The person who has more experience with drugs, or the person who was cleaner -- although it's unclear which is which.