Not the same issue, but my current fort has traders that scatter in all 4 directions when they leave. They all come in from the same side of the map, but when they leave they go *everywhere*. I had to build walls and channels to funnel the wagons out the one side, because wandering one humped camels kept killing wagons on the way out and flooding the countryside with crap.
With the wagons limited to one side, they all quickly leave there, but then the guys with mules and such wander all over the map. This latest caravan had one guy go north, one guy go south, and one go west. The other followed the wagons east. And the crazy caravan guards just go all over the place running back and forth between the traders while they're leaving, inevitably running into some kind of wildlife. Last dwarven caravan they had a guard stay around till winter chasing a one humped camel back and forth across the map. He eventually died to the goblin invasion.
I thought caravans were supposed to be a group of traders who travel together. Apparently my fort has become some kind of merchant travel hub, where everyone shows up once a year from the mountainhomes and then splits up to their many different destinations. How my exports ever make it back to the mountainhomes to be counted is beyond me.