For the pitot-static system, proper, I can't bring to mind any aircraft which uses both a combined head and fuselage static ports - there should be no reason to do so.
The pitot bit is comparatively straightforward and, providing that dimensions are reasonable, errors generally aren't a major concern.
The static bit, on the other hand, can present significant difficulties to the designers to get within acceptable error boundaries. As to whether the designer goes for a combined mount or fuselage statics is up to the designer's assessment of which is the better way to achieve the design standards requirements.
If you are looking at an aircraft with both a combined head and fuselage statics, my guess would be that the fuselage statics are for some other purpose than the pressure instrument panel ?