In reply to sjc:
The opposite happened to us in the Dolomites last summer. Guide in front on a single rope, we on 60 metre twins. Guide runs two pitches together that our topo says would be more than 60 metres. "Oh", says we, "his single rope must be a 70". Uncomfortable semi-hanging belay between two pitches that, as it turns out, we could easily have done in one with our 60s.