I came accross this article on “want to improve your qualitative research? try using representative sampling and working in teams” and I found interesting the advantages authors highlight with regard to do interviews in pairs:

Teamwork was woven into all aspects of the project. For example, we often interviewed in pairs. This was partly for safety, but also because it was easier for one person to drive while the other navigated, to call a youth to let him know we were on our way, or to begin writing the field notes on the return trip home. But the primary reason is that it improved the quality of the data. We have all watched each other conduct interviews and given feedback on how the other person could have done it better, or what was missed. We debriefed as a team on a weekly (sometimes daily) basis, talking about the day’s interviews, what we noticed, what surprised us, and what patterns we were observing. Was there something in the interview guide that needed updating because of recent events? Did the team understand the terminology someone used when describing her sexual or romantic relationships?

An additional advantage to team research is that it’s much harder to make a mistake when others who read and comment on your work have all been in the same neighborhoods, interviewed others from the same family, and have read the same transcripts. Often, during the course of analyzing and writing, we were challenged by colleagues who questioned whether a given conclusion is warranted. That kind of feedback sent us back to the drawing board more than a few times.