How do you avoid the problem of a collaborative work having separate voices?
I've not done collaborative writing before, but I've read several works, and sometimes the text strikes me as having a split personality: some parts were clearly written by one author, while others were written by another. (Note: I would give examples, but I can't remember any off-hand because I'm a bit sleep-deprived at the moment!)
So, the story itself is cohesive, but lacks a unified voice, so much so that it's distracting. Obviously, authors have very distinctive styles, and this can shine through very easily, so my question is really how do you ensure a unity of voice, or at the very least, incorporate the distinct voices of the authors in such a way that it isn't glaringly obvious that two different people were writing?
Would this come down to the editing process, or should you look at structuring the story in such a way that it can accommodate these different voices e.g. different narrators, POV's etc.?