Here in NYC I have installed metal boxes back to back in sheetrock walls. The last time I did this sort of work was about 5 years ago. It was for a New York State Agency in a Federal building. Installed as designed by the Architecht. They were extremely (anally) concerned about box placement.

We had no firestopping between the boxes (not that there was any room for it).

No questions from the inspectors.

However - like Ken said - Hospitals are going to be a different story anywhere. I did the infectious disease wing for Belleve Hospital and everything was firestopped AND sealed.

And like Hal said - every jurisdiction can and will make up their own rules. Get your answer first - and get it in writing.

Sam

"Where are we going and why are we in this hand basket?"