What version of Factorio and what version of the mod? And by "copying and pasting" you mean via a blueprint, yes? If you can reproduce this, please send the blueprint string you are pasting (paste, then place in your hotbar, right click, and export blueprint string) so I can try to reproduce it.
This mod only changes the "backer name" of an entity, and not the actual name, so the only way I think this could be happening is if your copy source didn't include train station names