Well, given that there are only 28-31 days in a month, and we can play with 2 different calendars to get the results we want, I don't think it's any more coincidental than any other number you could pick. What about his birth, Alexei's birth, his father's death, Khodynka field, the Spala incident. that actual dates of the revolutions (only one of which was in 1917 btw), Rasputin's death, family assassinations and deaths, any relevant dates for WW1 (battles, beginning, taking command of the army)- all fateful dates, but were any on the 17th in either calendar? Possibly . But there are hundreds -possibly thousands- of events that happen in the life of an monarch and his country during his lifetime. It would be statistically impossible for some of them NOT to have the same date.