In a modular home there are 2 bathrooms on the same floor(upstairs bedrooms).I noticed on the bath circuits there are double pole breakers,1 for receptacles(20A)and 1 for lighting(15A).My question is are multi-wire branch circuits allowed in bathrooms? And if these are not multi-wire are DP breakers allowed to shut off power in separate bathrooms,or any rooms for that matter? I did not take off the panel cover to see if they were separate circuits or multi-wire circuits.I didn't think that the GFCI receptacles would work on a shared neutral.

Mulit wire circuits are allowed. Double pole breakers are allowed. Shared neutral will work if not fed through the gfci.

Gserve,
I'm a little confused here. Are you saying you have a double pole breaker that is half 20amp and half 15amp?

No, Each lighting circuit is on a 15A DP breaker and the outlets are on the 20A DP breaker.(2 separate bathrooms on the same floor).