Here in England, the rule is that all parts of any degree can be conferred on two Candidates at once, but not more than two. However, it's not encouraged: most Lodges prefer to give each degree separately to each Candidate to keep it as personal as possible, and especially the Third which is ritually awkward with two simultaneous Candidates. In special circumstances, dispensation is available from GL to confer the same degree on more than two Candidates at the same time, but that's very rare.
In one of my Lodges we went through a very busy patch a few years ago, when for a couple of years we had so many Candidates that we were struggling to fit them all into our timetable. We gave away all of the Second degree work to neighbouring Lodges as courtesy conferral requests, but even so we were overwhelmed by the demand. Therefore we often had to confer the same degree to two Candidates in the same meeting ... but nevertheless, we didn't like "double" ceremonies, so we worked each ceremony twice in the same meeting, except giving the lecture at the end jointly. On one occasion during that period, we ended up having to do two Firsts and two Thirds all on the same day ... so we began in the morning, called off for a lunch break, then continued all afternoon! A very long day's masonry, that one. But quite exceptional over here, I've never seen anything like that again.
T & F,
Huw
