Is it legal for 2 motorcycles to leave from a stop sign and cross the intersection at the same time (side by side)

I guess if there is no "race" or "stunt" involved, then why not?

I hope so, but I'm pretty sure it's not or even if it is, it could still result in a charge. A bit of a drag on group rides, but that's why we keep our groups capped at 8. I hate seeing 20-50 cruisers going through a stop with the lead or sweep blocking the traffic and then doing 10 below the limits, while their formation is too long to safely pass unless you're riding a liter bike and don't mind risking getting 203'd.

I don't remember there being anything saying that two vehicles cannot occupy the same marked lane (although it seems like it should be a law!). Section 154 just requires the vehicle to be driven entirely within a marked lane. Anyone know differently?

In a turn, the outside rider would technically be in violation of the relevant subsection of section 141, by either not keeping to the edge of the roadway (right turn), or not keeping immediately to the right of the centre line (left turn).

Would be a huge stretch, but "stunt driving" could be interpreted to fit:

"...

iii. driving a motor vehicle in a manner that indicates an intention to drive, without justification, as close as possible to another vehicle, pedestrian or fixed object on or near the highway, or

..."

I was thinking more in line with "These two jokers with Kawasaki Vulcan 1500's revved it all the way up into the red line from the stop line to the speed limit, which seemed like racing, so I wrote them both 'racing' tickets" explanation.