My thoughts also but you follow the child's lead. If one wanders off then 'play' with the other one, encourage more interaction from them but also keeping an eye on the one that escaped as ofsted also want them to be individual and choose resources themselves. It's a juggling act, but we do it all day long, we just are't always aware of it.
I'm also trying to imagine my inspections day, but as I've got 5 lo's over 4 days, different combinations, it's hard to plan ahead.