I agree it's a shame that it could affect the relative impressions of that group. Yet personally I would say nothing. It's not appropriate to read other people's work/notes even after a test is over, in order to see that so many written out answers were the same she was not minding her own business (though I fully understand that once a accidental glance shows a similar pattern one would be alarmed and naturally look more closely). And it's clear that not every answer was the same, or the same score would have been obtained. A cheater often will intentionally keep answers from being identical, but it does make proof more difficult.
If you think it essential then an anonymous note in a teacher's box saying there was a concern of copying by the girl, without specific reference, would alert school staff to watch her in the future. And it might globally serve to make them rethink their test seating arrangements.
This is a good opportunity to show your DD how to protect her own tests from view by use of scratch paper on top of the questions she is not currently working on, her own hair if it is long, or non-dominant arm blocking view of the paper, etc. Some of those things in conjunction make cheating much more difficult. Yes this should not be necessary but as a smart kid she will always be a target for people to cheat. Preventing copying in the first place protects her from accusations of, "no she cheated off of me", which is often what a cheater will say in their defense. That clever retaliation flips suspicion onto your daughter and needs to be avoided.
Polly
