SD2
In the case you described, the ceiling is most likely not a 1-hour horizontal assembly. Its just a ceiling. Your installation complies with NFPA 13 and Chapter 7 of the IBC, which governs fire-resistance rated construction. Two layers may have been applied because of energy code implications or the architect was trying to reduce the sound transmission level.
My recommendation to fire protection design professionals is to be sure to know where vertical and horizontal assemblies are located. When you penetrate them, a through penetration fire stop assembly is generally required. This can be difficult, especially in older buildings without architectural plans. In this case, I recommend retaining a fire protection engineer or an architect so that height and area calculations can be performed to determine if the wall is a fire partion, fire barrier or fire wall or if horizontal assemblies are required.
What Travis has is a ceiling that was constructed as a 1-hour horizontal assembly. You will usually find these in corridors that have excessive travel distances. You can also find these in the floor/ceiling assemblies of high-rise buildings. If they are penetrated, then a through penetration fire stop assembly is required.