It seems like nowiki-tags show up at edits done at nowiki with VisualEditor.
The first of the two examples (https://no.wikipedia.org/w/index.php?title=Cologne_Business_School&diff=13473599&oldid=13473538) could be a copy-paste. If so it is an user error and the same as in Bug 68928 VisualEditor: Copy/pasting causes <nowiki> and <em> tags to appear.
The second edit seems to be different (https://no.wikipedia.org/w/index.php?title=Bergen&diff=prev&oldid=13467156) and I'm not sure what has happened here. Perhaps it is Bug 49820 - VisualEditor: When user types in '[[' in the page or another DOM input widget, pop up a reminder that they're using VisualEditor. If this is the case the user has clicked through a warning (has it failed?) and still saved.
There is a thread at nowiki about this, https://no.wikipedia.org/wiki/Wikipedia:Torget#Tomme_nowiki-tagger ("Empty nowiki-tags")
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