OK, this is actually in my house. I tore out a 1/2 wall that divided our family room and dining room this evening. The wall had receptacles on both sides, and it turns out they are are two different circuits and are in the middle of those circuits so I can't just go to the upstream boxes and disconnect the wiring feeding them. At least one is going to be moved into the adjacent wall. The other I have three options I've thought of:
1) Open up the wall, drill down into the basement, run the wiring down into a junction box down there. I don't like this because it will mean more drywall repair work than I currently need to do.
2) Install two single junction boxes and move both circuits into the wall. I think this will look dumb.
3) The option I'm currently leaning towards is to put in a double box and put both receptacles in that box. This would mean two different circuits in the same box. Not sure that is kosher.