I think the balance between two supplying factories will depend on the total journey time from factory to industrial building in the town, won’t it? If both factories are delivering to the same goods station then it will come down to the line frequencies, and you would expect the fastest delivery to win in the end.
Bastagre: for platforms divided into two (A/B sides – some UK stations use this arrangement too, for example York P5a/5b, but not in that case with simultaneous, opposite arrivals and departures), just place two stations end-to-end! A junction between wouldn’t work without enough space though.