Worlds branching or diverging in Many-Worlds Interpretation? In recent years there seems to have been a growing discussion surrounding MWI's ontology.
In the 2010 volume "Many Worlds?", Simon Saunders has a chapter dedicated to discussing whether the worlds in MWI branch or diverge.
The branching view states that before a measurement there is 1 observer in 1 world, after the measurement there is 2 observers in 2 worlds.
The divergent view states that there were 2 observers and worlds all along, but they were identical up to the point of differentiation, so there were no way for you to tell which world you were really in.
Alastair Wilson has written several papers on this in the last years: http://alastairwilson.org/
Any MWI proponents got any opinion either way?
 A: The two interpretations only differ in ontology. Neither is bullshit, rather both are standard MWI. When you have an observer, this is a computational entity, and to map it to a wavefunction is a nontrivial task. Whether you decide to say there were "really" two observers that were exactly the same before the measurement or whether there was "really" only one observer which branched is a meaningless question in the sense of Carnap, and has no answer, not even philosophically.
The important principle is that the "number" of consciousnesses is determined by interaction with other entities. If you have a computer running a simulation of a conscious observer, and you decide to do a double-check step on each computational step, do you get a second observer? If you do the double-checking in a different computer, is it a new observer? Observationally, you only get a new observer when you talk to two different people, and this only happens after the two computations are distinct.
This question is entirely about philosophy of mind, and this is where computational and positivist formulation is most important.
