This happens on all types of servers so it doesnt seem to be GRF related nor unofficial client related.
Enjoy PBS bug :)
Oh btw.. I have a small clue how to replicate it (obviously as it nearly happens all my games when i do this). It seems to have something to do with a train (the one on station platform) getting a forced pullout from depot (skip signal click) and after that another train incoming where you can visually see it is reserving per PBS, but ones it comes to the last PBS it thinks the platform is empty?
As you can see in this save game i tried it 2 more times before which failed, so its very inconsistent to replicate. They followed the same procedure which is making a new train (I.E the last one who gets crashed into) which has to be forced out via the skip signal as the rails downwards are full of trains already without any signals on it.
The train driving upwards that is crashing into the top station train were not forced out as it was the first train.
I made the rail connection at the top station and signals after the last train were forced out, so it didnt have any influence from any other signals except the depot itself.
Ive had this happening all from one PBS up to 20:ish passings with the same result, a crash.
Thanks for this. There's been no activity on this for some time, and as it stands, it doesn't look likely that it will go any further. I'm closing it as we try to keep the issue count low for OpenTTD, it helps us focus on things that are important and fun. Feel free to discuss in irc or request re-opening if you disagree. Thanks for contributing!