Sorry for digging up this old topic.
Still I have not made it clear why even a unique station name was sometimes renamed to another name when Simutrans loads the game. I found that there are no code to reset the state of haltestelle_t::all_names in simhalt.cc.
Anyway, is there any practical reason to preserve the renaming process in haltestelle_t::finish_rd()?
The current simutrans code should work fine with duplicated station names. IMO, renaming station names without any alert results confusion of players and makes no benefit.
I commented out
simhalt.cc:L2917-2939 in my repository and had some Japanese players test this. They reported that this modification seemed to suppress unexpected station renaming which happens in a game loading. Furthermore, they said that this reduced disconnection of a network game.
Therefore, I think the station renaming process is obsolete and should be removed. Removing simhalt.cc:L2917-2939 would be enough.