Yep, basically. And whichever other means of identification they wish to have.
Correct, the main reason for that being is, that people will just end up appending Numbers to their Name or adding a "The Real " in front of their name, even though nobody else with their Name is on that Server. Also encourages people to come up with a Name for each “Character” they play instead of being coerced into using their Internet-World-Name.
That would require centrally signing that cert though, which I am not willing to do.
Using differing Tick Rates can explode GT6 Machines, it is already something happening on certain Bukkit-ish Servers.