It is typical of a Fassbinder film that all would muck in when called upon to do so, and this it appears would operate on several tiers. Therefore, when it came to dubbing Effi Briest, and when - we must presume - that Hark Bohm was no longer available, the job fell to Kurt Raab. Perhaps Raab was at hand, and was cheaper, but it would have been unlikely that he could have been first choice. Raab’s voice is smooth and always slides along from word to word, whereas Bohm’s own voice, more meancing and quiet, would have been better for the role of Apotheker Gieshübler.
However, so it stands in this strangely dubbed mix-up, that many of the Fassbinder regulars seem to swap voices and bodies, quite apt really, and almost a joke in itself. I also hate to say this, but Raab doesn’t appear to be too good at the dubbing process, and the fact that he is permanently waiting for the visual cue (the motion of Hark Bohm’s lips) make the character seem much more stilted than he actually should be.
This YouTube upload is of Effi Briest and if you run it to the 21:50 minute mark, you will hear Kurt Raab's dubbing, as he voices the character of the apothecary.
This link will take you directly to 21:50 in Fassbinder's Effi Briest Fassbinder's Effi Briest at which you will hear Kurt Raab speaking from the mouth of Hark Bohm.