no, its just creative engineering. You have your block segments set up to think that the block is clear, or your brakes just dont work and let the trains go. Or it could just be a bug lol
You may for instance achieve that easily with a station brake setting that is too weak to fully stop the second car following into the station, thus sending it out right behind the first.
Yep, i had that too, with braking experiments gone bonkers...