Curt, with any motor with less than 10HP (7.5KW), no, you don't need a number. I would however, paint over those bogus numbers.
There's a difference between boat registration and licensing. You'll probably never need to register your boat. You will however, need to license your boat should you have a motor of 10HP or greater( that's why motors are labeled 9.9 by the way). Boat licensing in Canada has nothing to do with ownership/title. It is just a means of identification for search and rescue. Licensing takes but a few minutes at any of the more than 300 Service Canada offices across the country and it's free.
If you need any other info on this, PM me. I might be able to help.