Answer: The usual thing when doing any kind of repeat is that inner repeats don't get taken the second time through. For instance, it's traditional in a Minuet and Trio for the Trio to be marked Da Capo al Fine: you go back to the top of the Minuet (the head, or capo), and run through it once more but without its inner repeats. It's not marked that way; it's just tradition. Same thing holds for Dal Segno (from the sign).

But as always, there is some room for debate.

Frederick Dorian (The History of Music in Performance) says, "In the performance of the classical minuet, there are certain established traditions. In the first reading, before the Trio, repeats are used. After the trio they are omitted."

"However," he continues, "in earlier times audiences were more tolerant of repetition...When the classical composers did not intend repetition the second time, they expressly marked in the score, da capo senza repetizione."

Here's an example of that: in the Peters edition of Mozart's Quartets K. 156 and 158, each is marked at its end of the trio: "Men. da capo senza repetizione" ("from the top of the minuet, without repeats.") Others in the same collection merely say, da capo. So one could think along with Dorian: in the other quartets maybe the repeats are really meant to be taken both times.

I think one could make a case that if the repeat includes a first/second ending, it would make sense to take it both times through - on the theory that the first/second ending means the repeat is not exact; it's just a way of writing a double phrase that first ends "open" and then ends "closed." That is one complete unit; it seems a shame to break it up.

But my first sentence above describes the general practice.