My 00 Jackal was starboard too.
My guess was always different batches of parts from suppliers in different years.
Or maybe in 00 they bought them in pairs, used starboard in 00 and port in 01 until they were gone then purchased again.
My thought is that they bought them in pairs, because the EV and Bassa/Special had dual disks in the front.
On the single brake Jackal, they simply used one side for one year, and the other side for the next.
The fork sliders had the bosses on both sides, so this was an easy way to get rid of the inventory.
Classic case of Guzzi using what is on the shelf at assembly time.