It's hard to judge what the best solution is. If the codes refer to different parts of the station, I would map them as such. If the station just has two codes, I'd add them in the main tag as a list.

Nevertheless, could you decide for one spelling of the suffix?
E.g. there are:
network:wikidata:Elizabeth_Line
network:wikidata:Elizabeth_line
network:wikidata:Elizabeth line