No, a humbucker in series sounds like a humbucker.
Your tonal difference between humbuckers and singles come from a couple of factors. One of the main factors is string sensing aperture. On singles the area that is sensed is narrower, hence u get a clearer (brighter) sound. On humbuckers, the aperture is wider (cos it spans over 2 coils) and u get some harmonics canceled out, giving u a darker sound.
Compared to ur positions 2 and 4, a parallel wired humbucker is different as the 2 coils that are active are closer together. Sounds closer to that of one singlecoil pickup rather than ur positions 2 and 4.
Anyway, no humbuckers are going to sound like a true singlecoil, due to the wide aperture. Even your stacked singles still sound different. I almost never run the stacked neck single on my anderson in stacked mode, always in true single mode. Its a compromise, hum vs tone. It's always ez to turn down the volume control when not playing. If you're getting excessive hum, chances are u have a shielding/grounding problem somewhere.