Understand that the military departments are commissioned under different goverment umbrellas (Conscription) than say overseas R.O.C. representative offices (Foreign Affairs) or even Immigration (Internal affairs) and that therefore, YOU WILL GET DIFFERENT ANSWERS ALL THE TIME.
Plus, sometimes I think that Chinese people, out of fear of being perceived as being wrong (cultural thing), sometimes speak with FULL confidence as if they know the answer, even if they don’t.
I have dual citizenship and though I am obviously not MALE, I did ask about this extensively as I was going through my own process of obtaining my R.O.C. passport many years ago and even visited the Conscription Departments in Taipei.
I have a lot of male friends who were born here but raised elsewhere like yourself who have gone through the process of obtaining their R.O.C. citizenship as described in the link above.
Know that OFTEN TIMES immigration branch offices themselves are NOT fully aware of the policies as issued by the Conscription Dpt. One of my friends who is from a smaller county down south was even told that he needed to register for the military on the spot! Which he later found out was not true.
Talk to the source. The Conscription Department here in Taipei. If you are still in Canada, you can also ask the R.O.C. overseas office there, but my guess is that they will not know (my nearest office did not know either), because cases like these are rare compared to what they normally deal with on a day to day basis.
Again, MOST government employees in departments other than the Conscription Dept. do not know the intricate details of your situation, especially in the overseas offices, as the reps typically must rotate in/out every so many years. Those who have had the “privilege” of handling such cases often move on, and new people that step in have no experience with this.
My rule of thumb when it comes to any R.O.C. regulations or policies is to go straight to the source and then ask 3 or 4 different people there. If you hear the same thing 3 or 4 times, then that is your answer. If you don’t, keep asking until you get 3 or 4 of the same answers.