Hi Magnus,
Somehow the check on other items using the same identifier didn't work at and the same identifiers got added to another item (the item is for one of two persons who seem to get mixed up everywhere, including most library catalogues and dewiki: Talk:Q1064802).
It looks like it re-added some of the problem identifiers without the check working.
In the meantime, we removed/readded/set them to deprecated on Q1064802. I'm not sure if this simplifies or complicates things for you.
Sorry, slightly confused: The last edit by Reinheitsgebot on no label (Q1064802) was on 11 January 2017...?
It's the initially discussed edit on Q26222216 that was redone: https://www.wikidata.org/w/index.php?title=Q26222216&action=history
Ah, because the original edits were reverted "in bulk", there is no (say) "P214 removed" edit in the revision history, which is what the bot is looking for. I will make it look for and P214 (and others)-related edits, which would include its own.
I hadn't thought of that, but the main problem is that Q1064802 already had the identifiers the bot added to Q26222216. Possibly this is due to Q1064802 not having P31=Q5.