Steps:
- Find an article with at least one reference used twice.
- Create article translation (tested on articles from en -> pl).
- Modify the named reference (e.g. re-generate the reference from url).
- Save translation as an article.
Result: only the 1st occurrence of the ref is modified. The 2nd occurrence (and 3rd etc) is left as-was.
This happened for me when translating:
https://en.wikipedia.org/wiki/Anna_Sharyhina
Example after translation:
https://pl.wikipedia.org/w/index.php?title=Anna_Sharyhina&oldid=59162417