One may have a leak, or a failed DPM in the floor that's letting in moisture.
Also, the orientation of the building can make a difference: if one hangar has a north-facing side wall, the other will be south-facing, so one will always be colder than the other.
Don't try to heat the hangar with a gas space heater - you will release loads of water into the air, so that would be a very bad way of trying to combat the problem
FBW