While modding, I came acros a nice bug, it also applies to vanilla.
Imagine 2 forces: force fA and force fB
A train on force fA: train tA
When I make a new train stop on force fA, I can choose an already existing stop name (backer_name) from the list, a list containing all train stop names of my force fA.
Let's say the other force fB also makes a train stop with that same name, his list didn't show that station name, becose it was on anoter force, but he could choose this manual. No problem.
The issue however, when a train paths to this stop, the train doesn't care about the force. Meaning the train tA could travel to the train stop of his force, fA, but also to the force fB (if it has a path).
The main issue for vanilla, quickly easly put together:
In the production challenge:
How nice that the 'enemy' drops of his resources at my station instead of his... wondering where his resources are goiing They guess a station name of the enemies (maybe stream snyping?) and send a nice big artillery train to the other base to destroy it from the inside out! 
For modding
My trains are pathing to the wrong force 
Kind regards,
lovely_santa
