Again, don't want to argue, particularly if Canadian code is different here, but I don't think you have to separately vent the 2nd toilet. Correct me if I'm wrong.
That said, it certainly wouldn't hurt anything, you'd do a 3x3x2 wye/45 to a 2" vent after the 2nd WC, then take it up above the highest flood plain (typ. 42") and tie it into the 3" vent with a santee (upside down).
Can someone give insight about the venting issue? I'm pretty sure you can put 3 WC on a single 3" line, with the vent between the first 2, and need no further venting, but I could be mistaken.
What I WOULDN'T do, is put both toilets into a double santee. Too many problems with that setup with today's toilets...