Having two Captains flying the aircraft (other than check airmen) is usually the result of a shortage of FO's. This phenomena usually is the result of pilot attrition - the younger pilots go off to better employers while the more senior Captains stay at their present employer.
As far as how this relates to CRM, it should not be an issue. Professionalism "should" prevail. No one (in most normal circumstances) has started off a career in multiple crew aircraft as a Captain - at least some small modicum of time has been spent as an FO even at some point in the career. Since this generality for the most part is the prevalent circumstance it should not be too much of a stretch for a Captain to fly as an FO. This presumption would require that the pilots operating as FO mutually accept and tolerate the other Captain's operational "techniques" and variations.
I speak of this from experience as I have had this occur. One leg I flew as Captain and the next as FO. It worked out ok, and both flights were safe operations without the presence of overwhelming strife or disagreement. I would say overall it was one of the easier set of flights that I have done.
On a side note we both received Captain's pay for both flights.
Last edited by FearlessFreep; 16th Aug 2005 at 16:22.