Here's a technique I use when presented with the right circumstances responding to a domestic dispute. Often one of the parties — usually the one who called — meets you outside of the residence as you approach, and the other party is in the first room inside the door.

Rather than bringing both parties immediately back into the same room, I keep the first party out on the porch as contact is made with the second inside. Once safety is assured (no weapons possessed, no medical assistance needed, etc.), and interviewing begins, I position in the doorway for the interview of the first party who is still outside the door, with a back-up officer on overwatch of the second party. Then it's just a simple change of positions to interview the second party.

This puts some barrier between the parties, interferes with them hearing their other's allegation (which often results in more attempts to argue, possible verbal intimidation, or a shouting match). If one or the other gets out of control, a door can be quickly pulled shut between the parties as officers take appropriate control of the situation.

Both officers can keep visual and verbal contact with each other in this manner, but these factors are removed from the disputing parties. I've used this effectively many times and found that, on the whole, tensions go way down compared to when both parties remain in the same room listening to each other rather, than telling the officer what happened.