Not that this applies to your particular situation of course but I have seen places where that duplication was actually warranted - especially in css. E.g. some

Not that this applies to your particular situation of course but I have seen places where that duplication was actually warranted - especially in css. E.g. some code was extracted and reused when it was not meant to, just drying the code up, but those things turned out not to be the same thing and it was rather painful when we had to change them independently. As to your particular case - I’m sure the politics of the situation were pretty bad but I’ve solved situations like this by having two separate commits/prs one that uses the old style to fix a problem so the change is obvios, the other to change all the old style to the new style of code. Helps the reviewer understand what’s happening and move the PRs along. Though this was in a much more liberal code review environment of course ...