As I’m reading the situation:
The author is implying that all the characters shouts in that moment is that it is “ウチの名を騙って,” but the author wants to keep things clear, since うち is so broad.
I actually brought it up today on a different topic, and I think the same is happening here
The furigana shows what is being said, while the kanji shows what is meant. Looks like a tense scene, so I guess it would feel wrong for the characters to be taking the time to shout such a long term at at each other.
So just reinforcing what うち is referring to, is my guess. 