Great find there Karin!
Eyeing things up closely I'm going to say these photos aren't from the same session (Nicholas's hair appears slightly longer in the first set than here), but certainly around the same time period. 1902 is actually a little further back than I was going to go, but these photos do look like a 34-year old Tsar much more than a stressed 48/49-year old which is what he would have been by early-1917.
One thing is for certain. Assuming the photo you posted is indeed from 1902, there's no way those other photos with Alix are from 1917. Nicky might have been renowned for his physical fitness but there's no way he didn't age considerably over the course of 14 to 15 years (as the previous "1917" photos would seem to suggest). We have plenty of other photographs to compare to from the abdication era, and he certainly doesn't look as youthful pre-middle age as he does here.
