It is not a bug but it is not supposed to happen either.

It is a consequence of a low recalculation rate of the train's path especially when they are at a rail signal.

It messes up stackers and the use of rail signals when used with multiple stations as seen in my previous reply.

It also is ...

The bug is still there in [0.17.45].

In action it looks like this:

https://preview.redd.it/rrj3owkx1y131.g ... aebc8e7309

https://imgur.com/a/N3az6xm