I see. Difficult situation (and can be one of the problems with a supplier doing audits!) I gather by 'all and sundry' that the auditor cc'd lots of people, thus escalating the issue, which isn't great practice on his part. At all.

You have my sympathy.
Given that the previous actions did
not successfully rectify the NCRs although they were
closed, I would tend to agree that opening new actions (even with cross-referencing) probably isn't the best way to do it. Any QM or auditor is going to wonder: are they trying to avoid taking proper action, or failing to recognise that the closure was not justified?
Proably better to 'bite the bullet' and admit previous closure was premature or unwarranted, and re-open the original. Especially if your customer/ partner/ auditor is jumping up and down and raising a great hoo-hah about it.
But it isn't true that this is never or should never be done.

I do occasionally close one or even more than 1 NCRs and transfer action to a new one (with cross-reference to the old), but only when it's sensible, logical and there's good reason for doing it, such as consolidating a few minor ones into one, or perhaps a big subsequent change in circumstances. Because otherwise the CA trail of what was actually done on what can get rather convoluted or muddy.
Marcelo, I do not agree that there is always and only ever One Single Root Cause for an NC. At all. Indeed, good root cause analysis may often find more than one cause. But if that is the way it 'must' be done for medical devices (is it? ), I guess one is stuck with it.