No, dd2 did not go to one nap any earlier. She has been a better sleeper all round. But I understand completely what you're saying about two naps interfering with #1's activities. I *thought* dd2 was ready for one nap at 1yo, but she just got more and more overtired, so we went back to two, but I really restricted the first nap (put her down at 9am, and woke her at 9.45am no matter how long she had been asleep for). The transition to one nap is going so well with her (sometimes I find her having that first nap is quite handy since it's quite early, then we can go out, and stay out a bit longer, rather than having to be back by 12 noon). However she has regularly had to miss the first nap, and somehow has coped so well. We have never made her do that every day, otherwise it severely backfired!
Anyway, that got a bit long!