We've already had Niklas Bäckström from Finland and Nicklas Bäckström from Sweden.
People within the same generation and cultural sphere often have similar type of first names because of strong name trends. Regarding the two Ahos, I guess Sebastian was just a fairly popular name to give to your kids in the Nordic countries in the late 90s? (and I don't think only because of the famous crab in
The Little Mermaid).
Without trying to sound too much like an amateur psychologist or Sigmund Freud here, I think some of it is partly subconscious, and some of it is just fitting in. You'll often hear parents say "oh, we thought we were super original with our name choice, but then everyone else named their kid the exact same name!" For instance, former teammates Scott Niedermayer and Joe Nieuwendyk both have hockey playing sons named Jackson.